GAS TURBINE ENGINE BLEED AIR FLOW CONTROL

FIELD

[0001]The present disclosure relates to a gas turbine engine and, more particularly, to bleed air flow control.

BACKGROUND

[0002]Gas turbine engines, such as turbofan engines, may be used for aircraft propulsion. A turbofan engine generally includes a fan and a gas turbine engine or core engine to drive the fan. The gas turbine engine includes compressor section, a combustor, and a turbine section in a serial flow arrangement. Some gas turbine engines extract high pressure air from the compressor section, known as “bleed air.” This bleed air can be used to pressurize a cabin of an aircraft, to provide cooling to one or more parts of the engine and/or to power one or more systems of the aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003]A full and enabling disclosure of the present disclosure, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0004]FIG. 1 is a perspective view of an exemplary aircraft in accordance with an exemplary aspect of the present disclosure.

[0005]FIG. 2 is a cross-sectional view of an exemplary gas turbine engine in accordance with an exemplary aspect of the present disclosure.

[0006]FIG. 3 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0007]FIG. 4 is a flattened plan view of an exemplary flow control device in accordance with an exemplary aspect of the present disclosure.

[0008]FIG. 5 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0009]FIG. 6 is a flattened plan view of an exemplary flow control device in accordance with an exemplary aspect of the present disclosure.

[0010]FIG. 7 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0011]FIG. 8 is a flattened plan view of an exemplary flow control device in accordance with an exemplary aspect of the present disclosure.

[0012]FIG. 9 is a flattened plan view of an exemplary flow control device in accordance with an exemplary aspect of the present disclosure.

[0013]FIG. 10 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0014]FIG. 11 is a flattened plan view of an exemplary flow control device in accordance with an exemplary aspect of the present disclosure.

[0015]FIG. 12 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0016]FIG. 13 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0017]FIG. 14 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0018]FIG. 15 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0019]FIG. 16 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0020]FIG. 17 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0021]FIG. 18 is a flattened plan view of an exemplary flow control device in accordance with an exemplary aspect of the present disclosure

[0022]FIG. 19 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0023]FIG. 20 is a plan view of an exemplary flow control device taken along the line 20-20 of FIG. 19 in accordance with an exemplary aspect of the present disclosure.

[0024]FIG. 21 is an enlarged cross-sectional view of a portion of a high-pressure compressor of the gas turbine engine as shown in FIG. 2, in accordance with an exemplary aspect of the present disclosure.

[0025]FIG. 22 is a block diagram depicting an example computing system according to exemplary embodiments of the present disclosure.

[0026]Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present disclosure.

DETAILED DESCRIPTION

[0027]Reference will now be made in detail to present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure.

[0028]The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. The term “at least one of” in the context of, e.g., “at least one of A, B, and C” refers to only A, only B, only C, or any combination of A, B, and C.

[0029]As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. Furthermore, the terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle, and are based on a normal operational attitude of the gas turbine engine or vehicle. More particularly, forward and aft are used herein with reference to a direction of travel of the vehicle and a direction of propulsive thrust of the gas turbine engine.

[0030]The term “turbomachine” refers to a machine including one or more compressors, a heat generating section (e.g., a combustion section), and one or more turbines that together generate a torque output. The term “gas turbine engine” refers to an engine having a turbomachine as all or a portion of its power source. Example gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, etc., as well as hybrid-electric versions of one or more of these engines.

[0031]The term “combustion section” refers to any heat addition system for a turbomachine. For example, the term combustion section may refer to a section including one or more of a deflagrative combustion assembly, a rotating detonation combustion assembly, a pulse detonation combustion assembly, or other appropriate heat addition assembly. In certain example embodiments, the combustion section may include an annular combustor, a can combustor, a cannular combustor, a trapped vortex combustor (TVC), or other appropriate combustion system, or combinations thereof.

[0032]The terms “low” and “high”, or their respective comparative degrees (e.g., -er, where applicable), when used with a compressor, a turbine, a shaft, or spool components, etc. each refer to relative speeds within an engine unless otherwise specified. For example, a “low turbine” or “low speed turbine” defines a component configured to operate at a rotational speed, such as a maximum allowable rotational speed, lower than a “high turbine” or “high speed turbine” of the engine.

[0033]As used herein, the terms “axial” and “axially” refer to directions and orientations that extend substantially parallel to a centerline of the gas turbine engine. Moreover, the terms “radial” and “radially” refer to directions and orientations that extend substantially perpendicular to the centerline of the gas turbine engine. In addition, as used herein, the terms “circumferential” and “circumferentially” refer to directions and orientations that extend arcuately about the centerline of the gas turbine engine.

[0034]Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 1, 2, 4, 10, 15, or 20 percent margin. These approximating margins may apply to a single value, either or both endpoints defining numerical ranges, and/or the margin for ranges between endpoints.

[0035]The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein.

[0036]The term “proximate” refers to being closer to one end than an opposite end. For example, when used in conjunction with first and second ends; high pressure and low pressure sides; or the like, the phrase “proximate the first end,” or “proximate the high pressure side,” refers to a location closer to the first end than the second end, or closer to the high pressure side than the low pressure side, respectively.

[0037]As used herein, the term “cruising speed” refers to operation of a turbine engine utilized to power an aircraft that may operate at a cruising speed when the aircraft levels after climbing to a specified altitude. A turbine engine may operate at a cruising speed that is from 50% to 90% of a rated speed, such as from 70% to 80% of the rated speed. In some embodiments, a cruising speed may be achieved at about 80% of full throttle, such as from about 50% to about 90% of full throttle, such as from about 70% to about 80% full throttle. As used herein, the term “cruise flight phase” refers to a phase of flight in which an aircraft levels in altitude after a climb flight phase and prior to descending to an approach flight phase. In various examples, cruise flight may take place at a cruise altitude up to approximately 65,000 ft. In certain examples, cruise altitude is between approximately 28,000 ft. and approximately 45,000 ft. In yet other examples, cruise altitude is expressed in flight levels (FL) based on a standard air pressure at sea level, in which cruise flight is between FL280 and FL650. In another example, cruise flight is between FL280 and FL450. In still certain examples, cruise altitude is defined based at least on a barometric pressure, in which cruise altitude is between approximately 4.85 psia and approximately 0.82 psia based on a sea-level pressure of approximately 14.70 psia and sea-level temperature at approximately 59 degrees Fahrenheit. In another example, cruise altitude is between approximately 4.85 psia and approximately 2.14 psia. It should be appreciated that, in certain examples, the ranges of cruise altitude defined by pressure may be adjusted based on a different reference sea-level pressure and/or sea-level temperature.

[0038]The present disclosure is generally related to high-pressure compressor bleed air extraction flow control for a gas turbine engine. A gas turbine engine generally includes a compressor section including a low-pressure compressor and a high-pressure compressor, a combustion section, and a turbine section arranged in serial-flow order. The compressor section includes a compressor casing that encases sequential rows of stator vanes and rotor blades of the low-pressure and high-pressure compressors. During operation, bleed air is extracted from the compressor at one or more locations and is routed into one or more respective bleed air cavities or plenums via respective bleed air channels. The bleed air is then distributed from the bleed air cavities via various pipes or tubes to cool turbine components and/or to service/support a variety of aircraft systems including but not limited to cabin air pressurization systems, air conditioning, fuel tank pressurization, thrust reverse system, fuel heating, anti-icing systems, etc.

[0039]Air bled from the compressor flowpath to the offtake cavity is circumferentially balanced to ensure that the bleed is not circumferentially distorted around the main air flowpath through the compressor. Circumferentially unbalanced bleed (arising from low pipe count, asymmetric port positions, or imbalanced port dimensions) circumferentially distorts airflow in the compressor flowpath, adversely impacting compressor operability. The need to keep compressor distortion within limits drives mechanical decisions, such as the number of bleed ports and pipes, their circumferential position, case radius, and flow dimensions (including variable areas, like a scroll).

[0040]Embodiments of the present disclosure includes features in the bleed air channels or bleed air cavities, or both, in combination with or independent of external features, to enable asymmetric bleed port geometry while maintaining compressor distortion within limits. In exemplary embodiments, various types of passive and/or active flow control devices such as, by way of non-limiting example, one or more baffles with features that vary circumferentially are used to manage compressor distortion with asymmetric bleeds. Embodiments of the present disclosure enable asymmetric bleed port geometry that prevents or reduces the need for a bleed cavity area increase or an offtake scroll to manage compressor distortion. Embodiments of the present disclosure include flow control devices that manage compressor distortion that may also be adjusted and/or modified after installation, allowing for improved compressor distortion and compressor operability on an individual gas turbine engine basis. Embodiments of the present disclosure manage distortion by either varying restrictions and/or pressure losses around a circumference of the bleed offtake and/or by adjusting the diffusion and/or pressure recovered downstream around the circumference of the compressor. Embodiments of the present disclosure include using apertures connecting to other cavities, such as neighboring bleed cavities or the undercowl, to manage the pressure in the bleed air cavity. The flow control devices of the present disclosure may be actuated and/or actively varied and/or may use material properties (e.g. thermal expansion) to passively vary the bleed airflow. Thus, embodiments of the present disclosure circumferentially balance air bled from the compressor flowpath. In other words, the flow control devices of the present disclosure maintain a uniform flow rate of the air around a circumference of the compressor casing.

[0041]Referring now to the drawings, FIG. 1 is a perspective view of an exemplary aircraft 10 that may incorporate at least one exemplary embodiment of the present disclosure. As shown in FIG. 1, the aircraft 10 has a fuselage 12, wings 14 attached to the fuselage 12, and an empennage 16. The aircraft 10 further includes a propulsion system 18 that produces a propulsive thrust to propel the aircraft 10 in flight, during taxiing operations, etc. Although the propulsion system 18 is shown attached to the wing(s) 14, in other embodiments it may additionally or alternatively include one or more aspects coupled to other parts of the aircraft 10, such as, for example, the empennage 16, the fuselage 12, or both. The propulsion system 18 includes at least one engine. In the exemplary embodiment shown, the aircraft 10 includes a pair of engines 20. Each engine 20 is mounted to the aircraft 10 in an under-wing configuration. Each engine 20 is capable of selectively generating a propulsive thrust for the aircraft 10. The engines 20 may be configured to burn various forms of fuel including, but not limited to unless otherwise provided, jet fuel/aviation turbine fuel, and hydrogen fuel.

[0042]FIG. 2 is a cross-sectional side view of an engine 20 in accordance with an exemplary embodiment of the present disclosure. In exemplary embodiments, the engine 20 may be a gas turbine engine. More particularly, for the embodiment of FIG. 2, the engine 20 is a multi-spool, high-bypass turbofan jet engine, sometimes also referred to as a “turbofan engine.” As shown in FIG. 2, the engine 20 defines an axial direction A (extending parallel to a longitudinal centerline 22 provided for reference), a radial direction R, and a circumferential direction C extending about the longitudinal centerline 22. In general, the engine 20 includes a fan section 24 and a turbomachine 26 disposed downstream from the fan section 24.

[0043]The exemplary turbomachine 26 depicted generally includes an outer casing 28 that defines an annular core inlet 30. The outer casing 28 at least partially encases, in serial flow relationship, an axial compressor section including a booster or low-pressure (LP) compressor 32 and a high-pressure (HP) compressor 34, a combustion section 36, a turbine section including a high-pressure (HP) turbine 38 and a low-pressure (LP) turbine 40, and a jet exhaust nozzle 42.

[0044]A high-pressure (HP) shaft 44 drivingly connects the HP turbine 38 to the HP compressor 34. A low-pressure (LP) shaft 46 that drivingly connects the LP turbine 40 to the LP compressor 32. The LP compressor 32, the HP compressor 34, the combustion section 36, the HP turbine 38, the LP turbine 40, and the jet exhaust nozzle 42 together define a core air flowpath 48 through the engine 20.

[0045]For the embodiment depicted, the fan section 24 includes a fan 50 having a plurality of fan blades 52 coupled to a disk 54 in a spaced apart manner. As depicted, the fan blades 52 extend outwardly from disk 54 generally along the radial direction R. Each fan blade 52 is rotatable with the disk 54 about a pitch axis P by virtue of the fan blades 52 being operatively coupled to a suitable pitch change mechanism 56 configured to collectively vary the pitch of the fan blades 52, e.g., in unison.

[0046]The engine 20 further includes a power gear box 58. The fan blades 52, disk 54, and pitch change mechanism 56 are together rotatable about the longitudinal centerline 22 by the LP shaft 46 across the power gear box 58. The power gear box 58 includes a plurality of gears for adjusting a rotational speed of the fan 50 relative to a rotational speed of the LP shaft 46, such that the fan 50 and the LP shaft 46 may rotate at more efficient relative speeds.

[0047]Referring still to the exemplary embodiment of FIG. 2, the disk 54 is covered by rotatable front hub 60 of the fan section 24 (sometimes also referred to as a “spinner”). The front hub 60 is aerodynamically contoured to promote an airflow through the plurality of fan blades 52. Additionally, the exemplary fan section 24 includes an annular fan casing or outer nacelle 62 that circumferentially surrounds the fan 50 and/or at least a portion of the turbomachine 26. The outer nacelle 62 is supported relative to the turbomachine 26 by a plurality of circumferentially spaced struts or outlet guide vanes 64 in the embodiment depicted. Moreover, a downstream section 66 of the outer nacelle 62 extends over an outer portion of the turbomachine 26 to define a bypass airflow passage 68 therebetween.

[0048]It should be appreciated, however, that the exemplary engine 20 depicted in FIG. 2 is provided by way of example only, and that in other exemplary embodiments, the engine 20 may have other configurations. Additionally, or alternatively, although the engine 20 depicted is configured as a geared gas turbine engine (e.g., including the power gear box 58) and a variable pitch gas turbine engine (e.g., including a fan 50 configured as a variable pitch fan), in other embodiments, the engine 20 may be configured as a direct drive gas turbine engine (such that the LP shaft 46 rotates at the same speed as the fan 50), as a fixed pitch gas turbine engine (such that the fan 50 includes fan blades 52 that are not rotatable about a pitch axis P), or both. It should also be appreciated, that in still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine. For example, in other exemplary embodiments, aspects of the present disclosure may (as appropriate) be incorporated into, e.g., a turboprop gas turbine engine, a turboshaft gas turbine engine, or a turbojet gas turbine engine.

[0049]During operation of the engine 20, a volume of air 70 enters the engine 20 through an associated inlet 72 of the outer nacelle 62 and fan section 24. As the volume of air 70 passes across the fan blades 52, a first portion of air 74 is directed or routed into the bypass airflow passage 68 and a second portion of air 76 is directed or routed into the core air flowpath 48, or more specifically into the LP compressor 32. The ratio between the first portion of air 74 and the second portion of air 76 is commonly known as a bypass ratio.

[0050]As the second portion of air 76 enters the LP compressor 32, one or more sequential stages of low-pressure (LP) compressor stator vanes 78 and low-pressure (LP) compressor rotor blades 80 coupled to the LP shaft 46 progressively compress the second portion of air 76 flowing through the LP compressor 32 towards the HP compressor 34. Next, one or more sequential stages of high-pressure (HP) compressor stator vanes 82 and high-pressure (HP) compressor rotor blades 84 coupled to the HP shaft 44 further compress the second portion of air 76 flowing through the HP compressor 34. This provides compressed air to the combustion section 36 where it mixes with fuel and burns to provide combustion gases 86.

[0051]The combustion gases 86 are routed through the HP turbine 38 where a portion of thermal and/or kinetic energy from the combustion gases 86 is extracted via sequential stages of high-pressure (HP) turbine stator vanes 88 that are coupled to a turbine casing and high-pressure (HP) turbine rotor blades 90 that are coupled to the HP shaft 44, thus causing the HP shaft 44 to rotate, thereby supporting operation of the HP compressor 34. The combustion gases 86 are then routed through the LP turbine 40 where a second portion of thermal and kinetic energy is extracted from the combustion gases 86 via sequential stages of low-pressure (LP) turbine stator vanes 92 that are coupled to a turbine casing and low-pressure (LP) turbine rotor blades 94 that are coupled to the LP shaft 46, thus causing the LP shaft 46 to rotate, and thereby supporting operation of the LP compressor 32 and/or rotation of the fan 50.

[0052]The combustion gases 86 are subsequently routed through the jet exhaust nozzle 42 of the turbomachine 26 to provide propulsive thrust. The pressure of the first portion of air 74 is also substantially increased as it is routed through the bypass airflow passage 68 before it is exhausted from a fan nozzle exhaust section 96 of the engine 20, also providing propulsive thrust. The HP turbine 38, the LP turbine 40, and the jet exhaust nozzle 42 at least partially define a hot gas path 98 for routing the combustion gases 86 through the turbomachine 26.

[0053]FIG. 3 is an enlarged cross-sectional view of a portion of the HP compressor 34 of the engine 20 as shown in FIG. 2. As shown in FIG. 3, the HP compressor 34 includes a casing 100. The casing 100 can correspond to the outer casing 28 (FIG. 2) or a portion of the outer casing 28. In particular examples, the casing 100 may comprise a plurality of casings. In exemplary embodiments, as shown in FIG. 3, the casing 100 includes an inner casing 102 radially spaced inwardly from an outer casing 104 with respect to radial direction R. The inner and outer casings 102, 104 may be coupled together by via fasteners such as bolts.

[0054]The inner casing 102 defines, forms, and/or otherwise surrounds a primary flow path 106 for airflow flowing aft or downstream through the HP compressor 34 to the combustion section 36 (shown in FIG. 2). As shown in FIG. 3, the HP compressor stator vanes 82 are coupled to and extend radially inward from the inner casing 102. The HP compressor rotor blades 84 are coupled to and extend radially outward from the HP shaft 44 (FIG. 2) and are disposed between successive rows of the HP compressor stator vanes 82. The HP compressor 34 may include multiple stages that progressively increase the pressure of the air flowing through the HP compressor 34 toward the combustion section 36 (FIG. 2).

[0055]In exemplary embodiments, the inner and outer casings 102, 104 define one or more openings or slots to extract high-pressure air from the primary flow path 106 of the HP compressor 34. This high-pressure air is referred to as “bleed air” because it is “bled” from the HP compressor 34. Bleed air is used for various purposes in the engine 20 and/or the aircraft 10. For example, bleed air can be used to cool or reduce the temperature of the HP and LP turbines. Additionally, or alternatively, the bleed air can be used to pressurize certain seals in the engine 20, which helps maintain tighter fittings and tolerances. Further, if the engine 20 is used on an aircraft, the bleed air can be used to power and/or provide a constant supply of air for one or more systems, such as an environmental control system (ECS) (which provides pressurized and temperature-controlled air to the cabin), a wing anti-icing system, and/or an engine anti-icing system.

[0056]In various embodiments, as shown in FIG. 3, the engine 20 includes a bleed air cavity 108 (e.g., a plenum, a collection chamber) defined between the inner casing 102 and the outer casing 104. In exemplary embodiments, the bleed air cavity 108 may also be referred to as a high-pressure (HP) bleed air cavity. During operation, bleed air is extracted from the primary flow path 106 and fills the bleed air cavity 108. One or more pipes 110 in the form of hoses or fluid lines are fluidly coupled to the outer casing 104 for routing (e.g., distributing) the bleed air from the bleed air cavity 108 through an offtake 111 of the pipe 110 to one or more downstream locations and/or systems 112. For example, the downstream locations and/or systems 112 can include the HP and/or LP turbine(s) 38, 40 (FIG. 2) (e.g., for cooling), one or more systems of an Environmental Control System (ECS) 113 such as but not limited to a cabin pressurization system, a wing anti-icing system, an engine anti-icing system, and/or any other location and/or system of the engine 20 or the aircraft 10 (shown in FIG. 1).

[0057]To supply the bleed air cavity 108 with bleed air, the inner casing 102 includes an opening 114. The opening 114 may be defined by a slot or aperture that extends through the inner casing 102 and circumferentially about the inner casing 102 with respect to circumferential direction C. In various embodiments, as shown in FIG. 3, the opening 114 defines a bleed air channel 116 that provides for fluid communication between the primary flow path 106 and the bleed air cavity 108. The bleed air channel 116 is at least partially defined by an upstream wall 120 that is axially spaced from a downstream wall 122 with respect to the axial direction A.

[0058]The bleed air channel 116 is formed, shaped and/or oriented to direct a portion of the airflow from the primary flow path 106 into the bleed air cavity 108 as a bleed airflow 118. During operation of the engine 20, a portion of the airflow (e.g., high-pressure air) in the primary flow path 106 flows through the opening 114 (e.g., as the bleed airflow 118), through the bleed air channel 116, and fills the bleed air cavity 108. In exemplary embodiments, the bleed air channel 116 is angled or slanted in the downstream direction (e.g., from left to right in FIG. 3). This enables the bleed airflow 118 to flow efficiently (in the generally downstream direction) into the bleed air cavity 108. In exemplary embodiments, the bleed air cavity 108 is filled with the bleed airflow 118 by receiving pressurized air from the primary flow path 106 at an upstream stage of the HP compressor 34 such as, but not limited to, the 4th stage of the HP compressor 34.

[0059]In operation, the flow of the bleed airflow 118 into the bleed air cavity 108 and the pressure in the bleed air cavity 108 depends on the demand from conditions of the downstream locations and/or systems 112, and the temperature of the bleed airflow 118 may depend on the operating aspects of the HP compressor 34 or flight phase of the aircraft 10 (FIG. 1). For example, during take-off or climb flight phases of the aircraft 10 (FIG. 1), the temperature of the bleed airflow 118 may be higher than the temperature of the bleed airflow 118 at a cruise flight phase. Further, air bled from the primary flow path 106 as the bleed airflow 118 is circumferentially balanced to ensure that the airflow in the primary flow path 106 is not circumferentially distorted. Circumferentially unbalanced bleed (arising from low pipe count, asymmetric bleed port positions, or imbalanced bleed port dimensions) circumferentially distorts airflow in the primary flow path 106, adversely impacting compressor operability. Accordingly, the need to keep compressor distortion within limits drives mechanical decisions, such as the number of bleed ports and pipes, their circumferential position, case radius, and flow dimensions (including variable areas, like a scroll). Exemplary embodiments of the present disclosure provide passive and/or active flow control for compressor bleeds that maintain allowable compressor distortion, while enabling asymmetric bleed port locations and flow areas.

[0060]In exemplary embodiments, the engine 20 includes one or more flow control devices 130 disposed at least partially within the bleed air channel 116 and/or the bleed air cavity 108 to passively and/or actively control the bleed airflow 118 within and passing through the bleed air cavity 108. The one or more flow control devices 130 may be located at one or more circumferential positions with respect to the inner casing 102 or with respect to a circumferential position of the one or more pipes 110. In FIG. 3, the one or more flow control devices 130 include one or more baffles 132 disposed at least partially within the bleed air cavity 108. The one or more baffles 132 may be oriented axially, radially, or a combination of both. The one or more baffles 132 may be crescent-shaped, drilled sheet metal, a mesh material, or any other suitable structure for regulating a flow of the bleed airflow 118 within and passing through the bleed air cavity 108. The one or more baffles 132 may include one or more apertures 134 for enabling the bleed airflow 118 to pass through the one or more baffles 132 from the bleed air channel 116 to the one or more pipes 110. The one or more apertures 134 may have varying sizes and densities (e.g., spacing between adjacently located apertures 134) based on a circumferential position of the one or more apertures 134, a radial and/or axial position of the one or more apertures 134, the circumferential position of the one or more apertures 134 with respect to the one or more pipes 110, or any combination of the foregoing. The bleed air channel 116 includes an inlet end 140 disposed proximate to the primary flow path 106 and an outlet end 142 disposed distal to the inlet end 140 and located proximate to the bleed air cavity 108. In the illustrated embodiment, the one or more baffles 132 are coupled to at least a portion of the wall 120 and extend radially outward and axially aft into a medial portion of the bleed air cavity 108. In exemplary embodiments, the one or more baffles 132 extend radially outward from the wall 120 and then transition axially aft to a divider wall 144 defining an aft boundary of the bleed air cavity 108. However, it should be understood that the one or more baffles 132 maybe otherwise configured, positioned, or coupled to the casing 100. In the illustrated embodiment, an axial location of the offtake 111 of the pipe 110 is aft of the bleed air channel 116. Accordingly, in exemplary embodiments, at least a portion of the one or more flow control devices 130 is located axially forward of the offtake 111 of the pipe 110. In other words, in exemplary embodiments, at least a portion of the one or more flow control devices 130 is located axially forward from the offtake 111 of the pipe 110 such that control of the bleed airflow 118 at least partially occurs while the bleed airflow 118 is flowing in the axially aft and/or radially outward direction.

[0061]FIG. 4 depicts a flattened view of at least a portion of an exemplary baffle 132 according to the present disclosure. In FIG. 4, the baffle 132 includes one or more series or sets of first apertures 134A sized larger than one or more series or sets of second apertures 134B. As depicted in FIG. 4, the circumferential locations and spacing between apertures 134 may vary based on a circumferential position of the one or more apertures 134, a radial and/or axial position of the one or more apertures 134, the circumferential position of the one or more apertures 134 with respect to the one or more pipes 110 (FIG. 3). In exemplary embodiments, the one or more second apertures 134B may be circumferentially located proximate to the one or more pipes 110 (FIG. 3) and the one or more first apertures 134A may be circumferentially located distal to the one or more pipes 110 (FIG. 3) such that the bleed airflow 118 (FIG. 3) is uniformly extracted circumferentially from the primary flow path 106 (FIG. 3) about a circumference of the inner casing 102 (FIG. 3). In exemplary embodiments, a flow rate of the bleed airflow 118 (FIG. 3) into an area or portion of the bleed air cavity 108 (FIG. 3) located proximate to the circumferential location of the one or more pipes 110 (FIG. 3) is equal to or substantially equal to a flow rate of the bleed airflow 118 (FIG. 3) into an area or portion of the bleed air cavity 108 (FIG. 3) distal to the circumferential location of the one or more pipes 110 (FIG. 3) so that the bleed airflow 118 (FIG. 3) is uniformly extracted circumferentially from the primary flow path 106 (FIG. 3) about a circumference of the inner casing 102 (FIG. 3). In other words, the second apertures 134B function to restrict the flow rate of the bleed airflow 118 (FIG. 3) into an area or portion of the bleed air cavity 108 (FIG. 3) more than the first apertures 134A to circumferentially balance the flow rate of the bleed airflow 118 (FIG. 3) into the bleed air cavity 108 (FIG. 3) with respect to the inner casing 102 (FIG. 3) based on a circumferential location of the respective apertures 134 and the circumferential location of the one or more pipes 110 (FIG. 3). Thus, the size and/or placement of the first and second apertures 134A, 134B function to vary or regulate the airflow extracted from the primary flow path 106 (FIG. 3) circumferentially about the inner casing 102 (FIG. 3) to circumferentially balance the airflow extracted from the primary flow path 106 (FIG. 3) despite an asymmetric location of the one or more pipes 110 (FIG. 3). In other words, the size and/or placement of the first and second apertures 134A, 134B function to equalize the flow of the bleed airflow 118 (FIG. 3) into the bleed air channel 116 (FIG. 3) between circumferential locations of the bleed air channel 116 (FIG. 3) proximate to and distal from the circumferential location of the one or more pipes 110 (FIG. 3).

[0062]FIG. 5 depicts another exemplary embodiment of the one or more baffles 132. In FIG. 5, the one or more baffles 132 are coupled to at least a portion of the wall 120 and extend into a medial portion of the bleed air cavity 108. In FIG. 5, the one or more baffles 132 are configured without the one or more apertures 134 (FIGS. 3 and 4). In exemplary embodiments, the one or more baffles 132 extend radially outward from the wall 120 and transition axially aft toward the divider wall 144. In exemplary embodiments, a length of the baffle 132 in the aft axial direction may vary based on a circumferential location of the one or more pipes 110. In exemplary embodiments, the baffle 132 may include a portion 150 extending radially outward from the wall 120 and a portion 152 that extends axially aft from the radial portion 150 toward the divider wall 144. An axial position of an aft end 154 of the portion 152 may vary circumferentially to create different size gaps 163 between the aft end 154 and the divider wall 144 at different circumferential locations. A length of the portion 152 that extends axially aft may vary based on a circumferential position of the portion 152 and the circumferential position of the one or more pipes 110. Alternatively or additionally, a radial location of the portion 150 and/or the portion 152 may vary based on a circumferential position of the respective portions 150, 152 and the circumferential position of the one or more pipes 110. In exemplary embodiments, the portion 152 may extend axially aft from the portion 150 a greater distance proximate to a circumferential position of the one or more pipes 110 than at circumferential positions distal to the circumferential position of the one or more pipes 110. In such a configuration, the portion 152 greater restricts the flow of the bleed airflow 118 exiting the bleed air channel 116 from reaching the one or more pipes 110 at circumferential locations proximate to the one or more pipes 110 while enabling more bleed airflow 118 to flow circumferentially toward the one or more pipes 110 exiting the bleed air channel 116 from circumferential locations distal to the one or pipes 110. The one or more baffles 132 may also circumferentially vary the diffusion of the bleed airflow 118 into the bleed air cavity 108 and, correspondingly, circumferentially vary the sink pressure that the bleed airflow 118 is exposed to about the inner casing 102. FIG. 6 depicts a flattened view of at least a portion of an exemplary baffle 132 according to the present disclosure as described in connection with FIG. 5. In FIG. 6, the portion 152 is depicted having a crescent shape extending in the axial direction. However, it should be understood that the portion 152 may have other geometric configurations and may increase or decrease in length in the axial direction at multiple circumferential locations. It should also be understood that the varying axial length of the portion 152 may be combined with the inclusion of the one or more apertures 134 as depicted in FIGS. 3 and 4.

[0063]FIG. 7 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 7, the one or more flow control devices 130 include one or more baffles 160 disposed within or proximate to the outlet end 142 of the bleed air channel 116. In exemplary embodiments, at least a portion of the one or more baffles 160 restrict or vary a flow of the bleed airflow 118 exiting the bleed air channel 116 at different circumferential locations with respect to the casing 100. In the illustrated embodiment, the one or more baffles 160 are disposed within the bleed air channel 116 such that at least a portion of the one or more baffles 160 extend from the wall 120 to the wall 122. However, it should be understood that the one or more baffles 160 may also be located at the outlet end 142 of the bleed air channel 116 or at other locations with respect to the bleed air channel 116. In exemplary embodiments, the one or more baffles 160 may include one or more apertures 162 enabling a flow of the bleed airflow 118 to pass though the one or more baffles 160 from the bleed air channel 116 to the bleed air cavity 108. In exemplary embodiments, similar to the one or more apertures 134 depicted in connection with FIGS. 3 and 4, the size and/or density of the one or more apertures 162 may vary based on a circumferential location of the one or more apertures 162, based on a circumferential of the one or more pipes 110, or both. In exemplary embodiments, the size and/or density of the one or more apertures 162 may be greater at circumferential locations distal to the circumferential location of the one or more pipes 110 than the size and/or density of the one or more apertures 162 at circumferential locations proximate to the circumferential location of the one or more pipes 110. In such a configuration, the apertures 162 restrict the flow of the bleed airflow 118 exiting the bleed air channel 116 at circumferential locations proximate to the one or more pipes 110 while enabling more bleed airflow 118 to flow circumferentially toward the one or more pipes 110 exiting the bleed air channel 116 from circumferential locations distal to the one or pipes 110.

[0064]FIG. 8 depicts a flattened view of at least a portion of an exemplary baffle 160 according to the present disclosure. In FIG. 8, the baffle 160 includes one or more series or sets of first apertures 162A sized larger than one or more series or sets of second apertures 162B. As depicted in FIG. 8, the circumferential locations and spacing between apertures 162 may vary based on a circumferential position of the one or more apertures 162 and/or the circumferential position of the one or more apertures 162 with respect to the one or more pipes 110 (FIG. 7). In exemplary embodiments, the one or more apertures 162B may be circumferentially located proximate to the one or more pipes 110 (FIG. 7) and the one or more first apertures 162A may be circumferentially located distal to the one or more pipes 110 (FIG. 7) such that the bleed airflow 118 (FIG. 7) is uniformly extracted circumferentially from the primary flow path 106 (FIG. 7) about a circumference of the inner casing 102 (FIG. 7). In exemplary embodiments, a flow rate of the bleed airflow 118 (FIG. 7) into an area or portion of the bleed air cavity 108 (FIG. 7) located proximate to the circumferential location of the one or more pipes 110 (FIG. 7) is equal to or substantially equal to a flow rate of the bleed airflow 118 (FIG. 7) into an area or portion of the bleed air cavity 108 (FIG. 7) distal to the circumferential location of the one or more pipes 110 (FIG. 7). In other words, the second apertures 162B function to restrict the flow rate of the bleed airflow 118 (FIG. 7) into an area or portion of the bleed air cavity 108 (FIG. 7) more than the first apertures 162A to circumferentially balance the flow rate of the bleed airflow 118 (FIG. 7) extracted from the primary flow path 106 (FIG. 7) and into the bleed air cavity 108 (FIG. 7) based on a circumferential location of the respective apertures 162 and the circumferential location of the one or more pipes 110 (FIG. 7). Thus, the size and/or placement of the first and second apertures 162A, 162B function to vary or regulate the airflow extracted from the primary flow path 106 (FIG. 7) circumferentially about the inner casing 102 (FIG. 7) to circumferentially balance the airflow extracted from the primary flow path 106 (FIG. 7) despite an asymmetric location of the one or more pipes 110 (FIG. 7). In other words, the size and/or placement of the first and second apertures 162A, 162B function to circumferentially balance the flow rate of the bleed airflow 118 (FIG. 7) equally between proximate and distal locations with respect to a circumferential location of the one or more pipes 110 (FIG. 7).

[0065]FIG. 9 depicts a flattened view of at least a portion of an exemplary baffle 160 according to the present disclosure. In FIG. 9, the baffle 160 includes a portion 164 that extends radially into the bleed air channel 116 from one or both of the walls 120, 122 varying distances circumferentially with respect to the inner casing 102. In FIG. 9, the baffle 160 may include a centrally disposed aperture 166 bounded externally by the portion 164 such that a size of the aperture 166 varies circumferentially based on a distance the portion 164 extends radially inward. Accordingly, the baffle 160 is configured to circumferentially balance the flow of the bleed airflow 118 (FIG. 7) flowing through the bleed air channel 116 (FIG. 7). In exemplary embodiments, the baffle 160 may be configured to reduce a flow of the bleed airflow 118 (FIG. 7) flowing through the bleed air channel 116 at circumferential locations proximate to a circumferential location of the one or more pipes 110 (FIG. 7) compared to the flow of the bleed airflow 118 (FIG. 7) flowing through the bleed air channel 116 at circumferential locations distal to a circumferential location of the one or more pipes 110 (FIG. 7). In other words, the baffle 160 functions to circumferentially vary or regulate the bleed airflow 118 (FIG. 7) extracted from the primary flow path 106 (FIG. 7) so that the flow of the bleed airflow 118 (FIG. 7) is uniform about a circumference of the inner casing 102 (FIG. 7) despite having an unbalanced or asymmetric circumferential locations of the one or more pipes 110 (FIG. 7).

[0066]FIG. 10 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 10, the one or more flow control devices 130 include one or more baffles 170 disposed within or proximate to the outlet end 142 of the bleed air channel 116. In exemplary embodiments, the one or more baffles 170 include one or more stationary baffles 170A and one or more movable or translatable baffles 170B. The baffles 170B may be movable or translatable with respect to the baffles 170A to circumferentially vary a flow of the bleed airflow 118 flowing through the bleed air channel 116 and into the bleed air cavity 108. In FIG. 10, one or more actuators 172 may be coupled to the one or more baffles 170B such that actuation of the one or more actuators 172 cause translatable movement of the one or more baffles 170B with respect to the one or more baffles 170A. The one or more actuators 172 may be communicatively coupled to one or more controllers 174 to automatically control the actuation of the one or more actuators 172 and the corresponding movement of the one or more baffles 170B. The controller 174 may be a stand-alone controller, dedicated to the downstream locations and/or systems 112, or alternatively, may be incorporated into one or more of a main system controller for the aircraft 10 (FIG. 1) (such as a full authority digital engine control system, also referred to as a FADEC), etc. The controller 174 may be configured similar to exemplary computing devices of the computing system 400 described below with reference to FIG. 22.

[0067]In exemplary embodiments, one or more sensors 176 may be at least partially located within the bleed air cavity 108 to detect at least one of a pressure within the bleed air cavity 108 or a flow rate of the bleed airflow 118 at one or more circumferential locations with respect to the bleed air cavity 108. The one or more sensors 176 may also be communicatively coupled to the one or more controllers 174 to receive feedback or data detected by the one or more sensors 176. In exemplary embodiments, based on the pressure within the bleed air cavity 108 and/or flow rate data received by the controller 174 from the one or more sensors 176, the controller 174 may be configured to automatically and independently control the flow rate of the bleed airflow 118 at one or more circumferential locations with respect to the bleed air cavity 108 via the one or more baffles 170A, 170B.

[0068]FIG. 11 depicts a flattened view of at least a portion of the exemplary baffles 170A, 170B of FIG. 10 according to the present disclosure. In the illustrated embodiment, the one or more baffles 170A include one or more apertures 180, and the one or more baffles 170B include one or more apertures 182. In the illustrated embodiment, the one or more apertures 180 are of a constant or same size while the one or more apertures 182 vary in size based on a circumferential location of the one or more apertures with respect to the inner casing 102 (FIG. 10). However, it should be understood that the sizing of the apertures 180, 182 may be reversed with respect to the baffles 170A, 170B, or the sizes of the apertures 180, 182 may be of a same size on both of the baffles 170A, 170B. In the illustrated embodiment, movement of the baffle 170B with respect to the baffle 170A, such as in a circumferential direction, controls the flow or varies an amount of the bleed airflow 118 (FIG. 10) that may pass through the baffles 170A, 170B (e.g., via the apertures 180, 182 based on the alignment or misalignment of the apertures 180 with the apertures 182. In exemplary embodiments, the baffle 170B may be configured with gear teeth 184 configured to correspondingly engage with gear teeth (not shown) of the actuator 172 (FIG. 10). Alternatively or additionally, one or more lever arms 186 may be coupled to the baffle 170B and the actuator 172 (FIG. 10) to facilitate movement of the baffle 170B with respect to the baffle 170A. It should also be understood that other types of actuation mechanisms may be used to facilitate movement of the baffle 170B with respect to the baffle 170A.

[0069]FIG. 12 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 12, the one or more flow control devices 130 are formed as part of or may be coupled to the wall 120. In exemplary embodiments, a geometric parameter of the bleed air channel 116 may vary circumferentially with respect to the inner casing 102 such that the cross-sectional area of the bleed air channel 116 varies circumferentially. As depicted in FIG. 12, the wall 120 may be spaced apart from the wall 122 at varying distances radially, axially, or both, at different circumferential locations with respect to the inner casing 102 to provide a circumferentially varied flow of the bleed airflow 118 through the bleed air channel 116 at the different circumferential locations. In exemplary embodiments, the wall 120 may be closer to or farther away from the wall 122 at various circumferential locations, depicted in dashed lines in FIG. 12, such that the geometry of the bleed air channel 116 varies circumferentially. In exemplary embodiments, a nominal position 190 of at least a portion of the wall 120 may extend circumferentially about at least a portion of the inner casing 102, and in various circumferential regions, at least a portion of the wall 120 may be disposed inwardly toward the wall 122 in a narrowed position 192 or may be disposed outwardly away from the wall 122 in an expanded position 194. Accordingly, in the narrowed position 192, the cross-sectional area or geometry of the bleed air channel 116 is at least partially reduced at or near the outlet end 142, as compared to the nominal position 190, to reduce a flow of the bleed airflow 118 at such circumferential locations. Correspondingly, in the expanded position 194, the cross-sectional area or geometry of the bleed air channel 116 is at least partially increased, as compared to the nominal position 190, at or near the outlet end 142 to increase a flow of the bleed airflow 118 at such circumferential locations. In exemplary embodiments, the nominal, narrowed, and expanded positions 190, 192, 194 may be circumferentially located based on a circumferential location of the one or more pipes 110. In exemplary embodiments, the wall 120 may be configured in the narrowed position 192 at a circumferential at or near the circumferential position of the one or more pipes 110, and the wall 120 may be configured in the expanded position 194 at a circumferential distal to the circumferential position of the one or more pipes 110. It should be understood that the wall 120 may gradually transition between the nominal, narrowed, and expanded positions 190, 192, 194 at different circumferential regions with respect to the inner casing 102.

[0070]In exemplary embodiments, the one or more flow control devices 130 may be formed as part of or may be coupled to the wall 122. In exemplary embodiments, the wall 122 is defined by an inlet end 196 located proximate to the primary airflow path 106. The inlet end 196 of the wall 122 is defined by a leading edge 198. In exemplary embodiments, the one or more flow control devices 130 are in the form of a varying radius of curvature of the leading edge 198 based on a circumferential location of the leading edge 198 to circumferentially balance the bleed airflow 118 into the bleed air channel 116. A reduced radius of curvature of the leading edge 198 may cause the leading edge 198 to capture additional high-pressure air from the primary flow path 106 to supply the bleed airflow 118 into the bleed air cavity 108 than a higher radius of curvature. In exemplary embodiments, the radius of curvature of the leading edge 198 may vary at different circumferential locations of the inner casing 102 to circumferentially balance the bleed airflow 118 into the bleed air channel 116. In exemplary embodiments, the radius of curvature of the leading edge 198 may be greater at circumferential locations proximate to the one or more pipes 110 than at circumferential locations distal to the one or more pipes 110.

[0071]FIG. 13 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 13, the one or more flow control devices 130 include the one or more actuators 172 coupled to or configured to apply a force to at least a portion of the wall 120. In exemplary embodiments, the one or more actuators 172 may be linear actuators configured to apply a force to at least a portion of the wall 120 to circumferentially vary a geometry of the bleed air channel 116. In exemplary embodiments, the one or more actuators 172 are actuable to move at least a portion of the wall 120 toward and/or away from the wall 122 to decrease or increase, respectively, a geometric parameter of the bleed air channel 116 such as, by way of non-limiting example, a cross-sectional area near the outlet end 142 of the bleed air channel 116. In exemplary embodiments, the one or more actuators 172 may include one or more members 195 that are extendable and/or retractable and coupled to or configured to apply a force to the wall 120. The one or more members 195 may be movable axially in the directions 197 to move the wall 120 in the directions 199 to decrease or increase a geometric parameter of the bleed air channel 116 such as, by way of non-limiting example, a cross sectional area of the bleed air channel 116. In exemplary embodiments, the one or more actuators 172 are communicatively coupled to the one or more controllers 174 to enable automatic control or actuation of the one or more actuators 172. In FIG. 13, one or more of the sensors 176 may also be positioned to sense or detect one or more of a pressure within the bleed air cavity 108 or a flow rate of the bleed airflow 118 within the bleed air cavity 108 and communicate the sensed or detected parameters of the bleed airflow 118 to the one or more controllers 174. Accordingly, based on the detected pressure within the bleed air cavity 108 and/or flow rate of the bleed airflow 118, the one or more controllers 174 may automatically control actuation of the one or more actuators 172 to vary a geometry of the bleed air channel 116 at various circumferential locations.

[0072]FIG. 14 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 14, the one or more flow control devices 130 include one or more segmented portions 200 of the wall 122 that are radially and/or axially movable or translatable with respect to the primary flow path 106. In exemplary embodiments, the wall 122 defining at least a portion of the bleed air channel 116 includes the one or more segmented portions 200, and the one or more segmented portions 200 are positioned proximate to the inlet end 140 of the bleed air channel 116. The one or more segmented portions 200 are coupled to one or more actuators 202. The one or more actuators 202 are actuable to translate or move the one or more segmented portions 200 in the directions 204 such that the one or more segmented portions 200 may be moved into or withdrawn from at least a portion of the primary flow path 106. In exemplary embodiments, the one or more segmented portions 200 may be moved into at least a portion of the primary flow path 106 to capture additional high-pressure air from the primary flow path 106 to supply the bleed airflow 118 into the bleed air cavity 108. In exemplary embodiments, the one or more segmented portions 200 may be moved into at least a portion of the primary flow path 106, or withdrawn from at least a portion of the primary flow path 106, at varying locations circumferentially about the inner casing 102 to circumferentially balance the bleed airflow 118 into the bleed air cavity 108. As depicted in FIG. 14, and similar to as depicted and described in connection with FIGS. 10 and 13, one or more of the sensors 176 and the one or more controllers may be used to automatically control the actuation of the one or more actuators 202 based on one or more of a pressure within the bleed air cavity 108 or flow rate of the bleed airflow 118.

[0073]FIG. 15 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 15, the one or more flow control devices 130 include one or more apertures 210 extending into one or more secondary cavities 212. In exemplary embodiments, the one or more secondary cavities 212 may be pressurized at a higher pressure than the bleed air cavity 108. In FIG. 15, the one or more apertures 210 extend through the divider wall 144 into the secondary cavity 212. In the illustrated embodiment, the secondary cavity 212 may also be a bleed air cavity located downstream from the bleed air channel 116 such that a portion of the air from the primary flow path 106 at a later stage of the compressor 34 is captured and directed into the secondary cavity 212. In exemplary embodiments, the one or more apertures 210 may be located circumferentially with respect to the inner casing 102 such that a local pressure increase in the bleed air cavity 108 proximate to such apertures 210 where a secondary airflow 214 enters the bleed air cavity 108 from the secondary cavity 212 reduces the flow of the bleed airflow 118 in that location. In exemplary embodiments, when the secondary cavity 212 is pressurized at a higher pressure than the bleed air cavity 108, the one or more apertures 210 may be positioned at circumferential locations proximate to the circumferential location of the one or more pipes 110. It should be understood also that the size and/or density of the one or more apertures 210 may vary based on a circumferential location of such apertures 210. In exemplary embodiments, the one or more apertures 210 may be in fixed positions and may function as passive flow control devices. However, in other exemplary embodiments, the one or more apertures 210 may be actuated between an open position, closed position, or partially open position such as, by way of non-limiting example, via one or more actuator-controlled valves 216. As depicted in FIG. 15, one or more actuators 218 may be coupled to the one or more valves 216 to automatically control actuation of the one or more valves for controlling the secondary airflow 214 into the bleed air cavity 108. Although not depicted in FIG. 15, the one or more actuators 218 may be communicatively coupled to a controller, such as the controller 174 (FIGS. 10, 13, and 14), such the controller automatically controls actuation of the one or more valves. In exemplary embodiments, although not depicted in FIG. 15, one or more sensors, such as the one or more sensors 176 depicted in FIGS. 10, 13, and 14, may be positioned within the bleed air cavity 108 such that actuation of the one or more valves is based on one or more of a pressure within the bleed air cavity 108 or flow rate of the bleed airflow 118 within the bleed air cavity 108.

[0074]FIG. 16 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 16, the one or more flow control devices 130 include one or more apertures 230 extending into one or more secondary cavities 232, such as an undercowl cavity. In exemplary embodiments, the one or more secondary cavities 232 may be pressurized at a lower pressure than the bleed air cavity 108. In FIG. 16, the one or more apertures 210 extend through the outer casing 104 into the secondary cavity 232. In exemplary embodiments, the one or more apertures 230 may be located circumferentially with respect to the outer casing 104 such that a local pressure decrease in the bleed air cavity 108 proximate to such apertures 210 where a portion 234 of the bleed airflow 118 exits the bleed air cavity 108 into secondary cavity 232 increases the flow of the bleed airflow 118 in that location. In exemplary embodiments, when the secondary cavity 232 is pressurized at a lower pressure than the bleed air cavity 108, the one or more apertures 230 may be positioned at circumferential locations distal to the circumferential location of the one or more pipes 110. It should be understood also that the size and/or density of the one or more apertures 230 may vary based on a circumferential location of such apertures 230. In exemplary embodiments, the one or more apertures 230 may be in fixed positions and may function as passive flow control devices. However, in other exemplary embodiments, the one or more apertures 230 may be actuated between an open position, closed position, or partially open position such as, by way of non-limiting example, via one or more actuator-controlled valves, similar to the valves 216 depicted in FIG. 15. Although not depicted in FIG. 16, a controller, such as the controller 174 (FIGS. 10, 13, and 14), and sensors, such as the sensors 176 depicted in FIGS. 10, 13, and 14, may be used in connection with such apertures 230 such that the flow rate of the portion 234 is controlled based on one or more of a pressure within the bleed air cavity 108 or flow rate of the bleed airflow 118 within the bleed air cavity 108.

[0075]FIG. 17 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 17, the one or more flow control devices 130 include one or more baffles 260 disposed within or proximate to the outlet end 142 of the bleed air channel 116. In exemplary embodiments, at least a portion of the one or more baffles 260 restrict or vary a flow of the bleed airflow 118 exiting the bleed air channel 116 at different circumferential locations with respect to the casing 100. In the illustrated embodiment, the one or more baffles 260 are disposed within the bleed air channel 116 such that at least a portion of the one or more baffles 260 extend from the wall 120 to the wall 122. However, it should be understood that the one or more baffles 260 may also be located at the outlet end 142 of the bleed air channel 116 or at other locations with respect to the bleed air channel 116. In exemplary embodiments, the one or more baffles 260 may include one or more apertures 262 enabling a flow of the bleed airflow 118 to pass though the one or more baffles 260 from the bleed air channel 116 to the bleed air cavity 108.

[0076]In exemplary embodiments, the one or more baffles 260 may be formed from at least two different materials having different material properties such that one or more portions of the one or more baffles 260 responds differently than one or more other portions of the one or more baffles 260 at different operating conditions of the engine 20. In exemplary embodiments, the one or more baffles 260 may be formed from at least two different materials having different coefficients of thermal expansion. In exemplary embodiments, a geometric parameter of one or more portions of the one or more baffles 260 may change based on a temperature of the bleed airflow 118. In exemplary embodiments, portions of the one or more baffles 260 formed from a material having a greater coefficient of thermal expansion property than another portion of the baffle 260 may deflect or expand to vary a flow rate of the bleed airflow 118 through the 260. Accordingly, the baffle 260 may be formed having the different materials positioned at different circumferential locations of the baffle 260 to circumferentially balance the flow rate of the bleed airflow 118.

[0077]FIG. 18 depicts a flattened view of an exemplary baffle 260 according to the present disclosure. In the illustrated embodiment, the baffle 260 may include an outer boundary 264 that would reside against or be in close proximity to the wall 120 (FIG. 17). The baffle 260 also includes an inner boundary 266 that defines the aperture 262. In the illustrated embodiment, the baffle 260 is formed having a portion 268 and a portion 270. The portion 268 may be formed of a material having a different material property different than a material used to form the portion 270. The portions 268 and 270 may be of any circumferential span and may be located at different circumferential positions about the baffle 260. In exemplary embodiments, the portion 268 is formed from a material having a coefficient of thermal expansion less than a coefficient of thermal expansion of the material used to form the portion 270. Accordingly, the portion 270 will experience greater deflection or expansion at elevated temperatures than the portion 268. The baffle 260 may be configured such that the portions 268 and 270 are circumferentially located about the inner casing 102 (FIG. 17) to circumferentially balance the flow rate of bleed airflow 118 (FIG. 17) with respect to the inner casing 102 (FIG. 17). Thus, in the illustrated embodiment, the inner boundary 266 in the regions of the baffle 260 corresponding to the portion 270 will deflect or expand inwardly in the direction 272 to decrease the size or geometry of the aperture 262. In exemplary embodiments, the portion 270 may be circumferentially located proximate to the circumferential location of the one or more pipes 110 (FIG. 17). In such an embodiment, during a climb flight phase of the aircraft 10 (FIG. 1), causing higher temperatures of the bleed airflow 118 (FIG. 17), the flow rate of the bleed airflow 118 (FIG. 17) would decrease near the circumferential location of the one or more pipes 110 (FIG. 17) due to the expansion of the portion 270. At a cruise flight phase of the aircraft 10 (FIG. 1), causing lower temperatures of the bleed airflow 118 (FIG. 17) than at a climb flight phase, the flow rate of the bleed airflow 118 (FIG. 17) would increase near the circumferential location of the one or more pipes 110 (FIG. 17) due to the portion 270 retracting from its expanded state in the climb flight phase. Thus, exemplary embodiments of the present disclosure utilize different materials having different material properties to form the one or more flow control devices to circumferentially balance the bleed airflow 118 (FIG. 17) to manage compressor 34 (FIG. 17) distortion.

[0078]FIG. 19 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 19, the one or more flow control devices 130 include one or more baffles 280 disposed within the bleed air cavity 108. In FIG. 19, the one or more baffles 280 are coupled to at least a portion of the wall 120 and extend into a medial portion of the bleed air cavity 108. In exemplary embodiments, the one or more baffles 280 extend at least partially radially outward from the wall 120 and transition axially aft to the divider wall 144. In exemplary embodiments, the one or more baffles include one or more baffle elements 281 including a portion 282 coupled to and/or extending radially outward from the wall 120 and a portion 284 extending axially aft from the portion 282 to the divider wall 144. In exemplary embodiments, the one or more baffle elements 281 include one or more apertures 286 to enable the bleed airflow 118 to pass through the one or more baffle elements 281. The one or more apertures 286 may vary in size and placement, radially, axially, and/or circumferentially, with respect to the inner casing 102.

[0079]In exemplary embodiments, the one or more baffles 280 also include one or more baffle elements 287 positioned to vary a size of the one or more apertures 286 or control an amount of the bleed airflow 118 passing through the one or more apertures 286. In exemplary embodiments, the one or more baffle elements 287 include one or more shutters 288 configured to be extendable over at least a portion of the one or more apertures 286 to vary a flow rate of the bleed airflow 118 passing through the one or more apertures 286. Similar to the baffle 260 depicted and described in connection with FIGS. 17 and 18, the one or more shutters 288 are formed of a material having a different material property than the material used to form the one or more baffle elements 281. In the illustrated embodiment, the one or more shutters 288 are coupled to the portion 284. The one or more shutters 288 are depicted on a radially outward side of the portion 284; however, it should be understood that the location of the one or more shutters 288 may be otherwise positioned with respect to the portion 284. The one or more shutters 288 may also be positioned at other locations, such as on the portion 282.

[0080]In exemplary embodiments, the one or more shutters 288 are formed from a material having a coefficient of thermal expansion greater than a coefficient of thermal expansion of the material used to form at least the portion 284. In exemplary embodiments, the difference in coefficients of thermal expansion between the one or more shutters 288 and the portion 284 enables the one or more shutters 288 to expand or deflect a greater amount than the portion 284 to vary a size of the one or more apertures 286 in response to varying temperatures of the bleed airflow 118. FIG. 20 depicts a plan view of the baffle 280 taken from the line 20-20 of FIG. 19. In exemplary embodiments, at least a portion 290 of the shutter 288 is coupled in a fixed location to the portion 284 proximate to a side 292 of the aperture 286. At least a portion 294 of the shutter 288 distal to the portion 290 is uncoupled to the portion 284 and is free to move with respect to the portion 284. In exemplary embodiments, as a temperature of the bleed airflow 118 (FIG. 19) increases, the shutter 288 expands causing the portion 294 to move in the direction 296 to decrease the geometry or size of the aperture 286. In response to a decrease in a temperature of the bleed airflow 118 (FIG. 19), the shutter 288 retracts from its expanded state causing the portion 294 to move in a direction opposite the direction 296 to increase the geometry or size of the aperture 286. The quantity and circumferential positions of the one or more shutters 288 may vary based on a circumferential location of the one or more pipes 110 (FIG. 19). In such an embodiment, during a climb flight phase of the aircraft 10 (FIG. 1), causing higher temperatures of the bleed airflow 118 (FIG. 19), the flow rate of the bleed airflow 118 (FIG. 19) would decrease where shutters 288 are located near the circumferential location of the one or more pipes 110 (FIG. 19) due to the expansion of the shutter 288. At a cruise flight phase of the aircraft 10 (FIG. 1), causing lower temperatures of the bleed airflow 118 (FIG. 19) than at a climb flight phase, the flow rate of the bleed airflow 118 (FIG. 19) would increase where shutters 288 are located near the circumferential location of the one or more pipes 110 (FIG. 17) due to the shutter 288 retracting from its expanded state in the climb flight phase.

[0081]FIG. 21 depicts another exemplary embodiment of the one or more flow control devices 130. In FIG. 21, the one or more flow control devices 130 are formed as at least a portion of the wall 120. In exemplary embodiments, similar to the embodiments of the one or more flow control devices 130 described and depicted in connection with FIGS. 17-20, at least a portion of the wall 120 may be formed from different materials having different material properties. In the illustrated embodiment, the wall 120 includes an inlet end 300 disposed proximate to the primary flow path 106 and an outlet end 302 distal to the inlet end 300 disposed near the outlet end 142 of the bleed air channel 116. The outlet end 302 of the wall 120 includes a portion 304 coupled to or disposed in contact with a portion 306. Similar to the baffle 260 depicted and described in connection with FIGS. 17 and 18, and the baffle 280 depicted and described in connection with FIGS. 19 and 20, the portions 304 and 306 are formed of materials having different material properties. In the illustrated embodiment, the portion 304 is formed of a material having a coefficient of thermal expansion greater than a coefficient of thermal expansion of the material used to form the portion 306. In exemplary embodiments, the difference in coefficients of thermal expansion between the portions 304 and 306 enables the portion 304 to expand or deflect a greater amount than the portion 306 to vary a size of the bleed air channel 116 at the outlet end 140 in response to varying temperatures of the bleed airflow 118.

[0082]In exemplary embodiments, in response to an elevated temperature of the bleed airflow 118, the portion 304 expands in a direction 308 a greater amount than the portion 306 causing the outlet end 302 of the wall 120 to deflect toward the wall 122 to a position 310 decrease the geometry or size of outlet end 140 of the bleed air channel 116. In response to a decreased temperature of the bleed airflow 118, the portion 304 retracts in a direction opposite the direction 308 a greater amount than the portion 306 causing the outlet end 302 of the wall 120 to deflect away from the wall 122 to a position 312 to increase the geometry or size of outlet end 140 of the bleed air channel 116. The circumferential locations of the portions 304 and 306 may vary circumferentially about the inner casing 102 to circumferentially balance or control the flow rate of the bleed airflow 118. In exemplary embodiments, the portions 304 and 306 may be circumferentially located based on a circumferential location of the one or more pipes 110 to increase or decrease a flow rate of the bleed airflow 118 at locations proximate to of distal from the circumferential location of the one or more pipes 110, similar to as described in connection with FIGS. 17-20.

[0083]It should be understood that one or more of the flow control devices 130 depicted and described in connection with FIGS. 3-21 may be used in combination. For example, and not by way of limitation, the one or more baffles 132 (FIGS. 1-6) may be used in combination with the movable portion 200 (FIG. 14). Additionally or alternatively, and not by way of limitation, the one or more baffles 160 (FIGS. 7-9) may be used in combination with the one or more apertures 210 or 230 (FIGS. 15 and 16). It should also be understood that different types of flow control devices 130 as depicted and described in connection with FIGS. 3-21 may be located at different circumferential positions with respect to the inner casing 102. For example, and not by way of limitation, the one or more baffles 132 (FIGS. 1-6) may extend semi-annularly or for a particular circumferential span and the one or more baffles 160 (FIGS. 7-9) may extend over a different semi-annular distance or different circumferential span.

[0084]FIG. 22 provides an example computing system 400 according to example embodiments of the present disclosure. The computing devices or elements described herein, such as the controller 174, may include various components and perform various functions of the computing system 400 described below, for example.

[0085]As shown in FIG. 22, the computing system 400 can include one or more computing device(s) 402. The computing device(s) 402 can include one or more processor(s) 402A and one or more memory device(s) 402B. The one or more processor(s) 402A can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and/or other suitable processing device. The one or more memory device(s) 402B can include one or more computer-executable or computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices.

[0086]The one or more memory device(s) 402B can store information accessible by the one or more processor(s) 402A, including computer-readable instructions 402C that can be executed by the one or more processor(s) 402A. The computer-readable instructions 402C can be any set of instructions that when executed by the one or more processor(s) 402A, cause the one or more processor(s) 402A to perform operations. In some embodiments, the computer-readable instructions 402C can be executed by the one or more processor(s) 402A to cause the one or more processor(s) 402A to perform operations, such as any of the operations and functions for which the computing system 400 and/or the computing device(s) 402 are configured, such as controlling operation of the actuators 172 (FIGS. 10 and 13), the actuators 202 (FIG. 14), and/or the valves 216 and/or actuators 218 (FIG. 15) to control the flow of the bleed airflow 118. The computer-readable instructions 402C can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the computer-readable instructions 402C can be executed in logically and/or virtually separate threads on processor(s) 402A. The memory device(s) 402B can further store data 402D that can be accessed by the processor(s) 402A. For example, the data 402D can include models, lookup tables, databases, etc.

[0087]The computing device(s) 402 can also include a network interface 402E used to communicate, for example, with the other components of the computing system 400 (e.g., via a communication network). The network interface 402E can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, and/or other suitable components. One or more devices can be configured to receive one or more commands from the computing device(s) 402 or provide one or more commands to the computing device(s) 402.

[0088]Thus, embodiments of the present disclosure includes features in the bleed air channels or bleed air cavities, or both, in combination with or independent of external features, to enable asymmetric bleed port geometry while maintaining a balanced or uniform flow rate of the air around a circumference of the compressor and maintaining compressor distortion within limits. In exemplary embodiments, various types of passive and/or active flow control devices that vary circumferentially are used to manage compressor distortion with asymmetric bleeds. Embodiments of the present disclosure enable asymmetric bleed port geometry that prevents or reduces the need for a bleed cavity area increase or an offtake scroll to manage compressor distortion. Embodiments of the present disclosure circumferentially balance the flow rate about the circumference of the compressor casing by either varying restrictions and/or pressure losses around a circumference of the bleed offtake and/or by adjusting the diffusion and/or pressure recovered downstream around the circumference of the compressor. The flow control devices of the present disclosure may be actuated and/or actively varied and/or may use material properties (e.g. thermal expansion) to passively vary the bleed airflow. Thus, embodiments of the present disclosure circumferentially balance air bled from the compressor flowpath to maintain a uniform flow rate of the air around a circumference of the compressor casing.

[0089]The technology discussed herein makes reference to computer-based systems and actions taken by and information sent to and from computer-based systems. One of ordinary skill in the art will recognize that the inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components. For instance, processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memory, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0090]This written description uses examples to disclose the present disclosure, including the best mode, and to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0091]Further aspects are provided by the subject matter of the following clauses:

[0092]An engine, comprising: a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel between the primary flow path and the bleed air cavity to direct a portion of the primary airflow as a bleed airflow into the bleed air cavity; and one or more flow control devices located at least partially within the bleed air channel, forming at least part of the bleed air channel, or extending axially aft from the bleed air channel, the one or more flow control devices configured to circumferentially balance a flow of the bleed airflow into the bleed air cavity or within the bleed air cavity.

[0093]The engine of the preceding clause, wherein the one or more flow control devices comprise one or more baffles, the one or more baffles comprising one or more apertures, wherein a size of the one or more apertures varies based on a circumferential location of the respective one or more apertures.

[0094]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, wherein the size of the one or more apertures circumferentially located proximate the one or more pipes is less than the size of the one or more apertures circumferentially located distal from the one or more pipes.

[0095]The engine of any preceding clause, wherein the one or more flow control devices comprise one or more baffles, wherein at least a portion of the one or more baffles extends axially in an aft direction with respect to the bleed air cavity, and wherein an axial length of the portion varies based on a circumferential location of the portion.

[0096]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein at least one of the axial length or radial location of the portion varies circumferentially based on a circumferential location of the one or more pipes.

[0097]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein the axial length of the portion is greater proximate to a circumferential location of the one or more pipes than the axial length of the portion located circumferentially distal from the one or more pipes.

[0098]The engine of any preceding clause, wherein the inner casing comprises a first wall and a second wall defining the bleed air channel, and wherein the one or more flow control devices comprise one or more baffles extending at least partially into the bleed air channel from at least one of the first wall or the second wall.

[0099]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein the one or more baffles are configured to equalize the bleed airflow flowing through the bleed air channel at circumferential locations proximate to the one or more pipes with the bleed airflow flowing through the bleed air channel at circumferential locations distal to the one or more pipes.

[0100]The engine any preceding clause, wherein the one or more flow control devices comprise: one or more first baffles; and one or more second baffles; and wherein at least one of the one or more first baffles or the one or more second baffles comprises one or more apertures, and wherein at least one of the one or more first baffles or the one or more second baffles is movable to control the flow of the bleed airflow through the one or more apertures.

[0101]The engine of any preceding clause, further comprising one or more actuators actuatable to move the at least one of the one or more first baffles or the one or more second baffles.

[0102]The engine of any preceding clause, further comprising: one or more sensors disposed within the bleed air cavity, the one or more sensors configured to detect at least one of a pressure within the bleed air cavity or a flow rate of the bleed airflow within the bleed air cavity; and a controller configured to control the one or more flow control devices to vary at least one of the pressure or the flow rate.

[0103]The engine of any preceding clause, wherein the one or more flow control devices are configured to vary a size of the bleed air channel.

[0104]The engine of any preceding clause, wherein a geometric parameter of the bleed air channel varies based on a circumferential location of the geometric parameter.

[0105]The engine of any preceding clause, wherein the inner casing comprises a first wall and a second wall defining the bleed air channel, and wherein the one or more flow control devices comprises at least a portion of at least one of the first wall or the second wall.

[0106]The engine of any preceding clause, further comprising one or more actuators actuatable to move at least a portion of the first wall to vary a size of the bleed air channel.

[0107]The engine of any preceding clause, further comprising one or more actuators actuatable to move at least a portion of the second wall into the primary airflow.

[0108]The engine of any preceding clause, wherein the second wall is disposed axially aft of the first wall and comprises a leading edge defining an inlet end of the second wall proximate the primary airflow, and wherein a radius of curvature of the leading edge varies based on a circumferential location of the leading edge.

[0109]The engine of any preceding clause, wherein the one or more flow control devices comprise one or more apertures extending from the bleed air cavity into at least one secondary cavity, wherein the secondary cavity is pressurized at a higher pressure or a lower pressure than the bleed air cavity.

[0110]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein the secondary cavity is pressurized at the higher pressure, and wherein the one or more apertures are located at or near a circumferential location of the one or more pipes.

[0111]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein the secondary cavity is pressurized at the lower pressure, and wherein the one or more apertures are located at or near a circumferential location opposite a circumferential location of the one or more pipes.

[0112]The engine of any preceding clause, wherein the one or more flow control devices comprise one or more baffles, and wherein the one or more baffles comprise a first material and a second material, wherein a coefficient of thermal expansion of the first material is greater than a coefficient of thermal expansion of the second material.

[0113]The engine of any preceding clause, wherein the one or more baffles comprise one or more apertures, and wherein the coefficient of thermal expansion of the first material causes a size of the one or more apertures to vary based on a circumferential location of the one or more apertures.

[0114]The engine of any preceding clause, further comprising one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein at least a portion of the first material is located proximate to a circumferential location of the one or more pipes.

[0115]The engine of any preceding clause, wherein the coefficient of thermal expansion of the first material causes a change in a size of the bleed air channel in response to a change in a temperature of the bleed airflow.

[0116]The engine of any preceding clause, wherein the one or more baffles comprise: one or more first baffle elements comprising one or more apertures, the one or more first baffle elements comprising the second material; and one or more second baffle elements fixedly coupled to the one or more first baffle elements, the one or more second baffle elements comprising the first material, the one or more second baffle elements positioned to vary a size of the one or more apertures in response to a change in a temperature of the bleed airflow.

[0117]The engine of any preceding clause, wherein the one or more baffles comprise: one or more first baffle elements, the one or more first baffle elements comprising the second material; and one or more second baffle elements fixedly coupled to the one or more first baffle elements, the one or more first baffle elements and the one or more second baffle elements defining at least a portion of the bleed air channel, and wherein the one or more second baffle elements are positioned to vary a size of the bleed air channel in response to a change in a temperature of the bleed airflow.

[0118]The engine of any preceding clause, further comprising: one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity; one or more sensors disposed within the bleed air cavity, the one or more sensors configured to detect at least one of a pressure within the bleed air cavity or a flow rate of the bleed airflow within the bleed air cavity; and a controller configured to control the one or more flow control devices to vary at least one of the pressure or the flow rate based on a circumferential location of the pressure or the flow rate.

[0119]The engine of any preceding clause, wherein at least a portion of the one or more flow control devices is located axially forward from an offtake of the one or more pipes.

[0120]The engine of any preceding clause, wherein the one or more flow control devices are configured to at least partially control the flow of the bleed airflow while the bleed airflow is flowing in the axially aft or radially outward direction.

[0121]The engine of any preceding clause, wherein the engine comprises a gas turbine engine.

[0122]An engine, comprising: a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity; one or more flow control devices located circumferentially about the compressor and disposed at least partially within at least one of the bleed air cavity or the bleed air channel, the one or more flow control devices comprising one or more actuators actuable to circumferentially balance a flow of the bleed airflow into the bleed air cavity or within the bleed air cavity.

[0123]The engine of any preceding clause, wherein the inner casing comprises at least one wall defining the bleed air channel, and wherein the one or more actuators are actuable to move at least a portion of the at least one wall to vary a size of the bleed air channel.

[0124]The engine of any preceding clause, wherein the inner casing comprises at least one wall defining the bleed air channel, and wherein the one or more actuators are actuable to move at least a portion of the at least one wall into the primary airflow.

[0125]An aircraft, comprising: a fuselage; a wing attached to the fuselage; and an engine, the engine comprising: a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity; and one or more flow control devices located at least partially within at least one of the bleed air cavity or the bleed air channel, the one or more flow control devices configured to circumferentially balance a flow of the bleed airflow into the bleed air cavity or within the bleed air cavity.

[0126]A method for operating an engine, the engine comprising a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity, the method comprising: detecting at least one of a pressure within the bleed air cavity or a flow rate of the bleed airflow within the bleed air cavity; and controlling one or more flow control devices to circumferentially balance the flow rate of the bleed airflow into the bleed air cavity or within the bleed air cavity based on the pressure or the flow rate.

[0127]The method of any preceding clause, wherein controlling the one or more flow control devices comprises actuating one or more actuators to vary a size of the bleed air channel.

[0128]The method of any preceding clause, wherein the one or more flow control devices comprise one or more baffles comprising one or more apertures, and wherein controlling the one or more flow control devices comprises actuating one or more actuators to vary a flow of the bleed airflow through the one or more apertures based on a circumferential location of the one or more apertures.

[0129]The method of any preceding clause, wherein the inner casing comprises a first wall and a second wall defining the bleed air channel, and wherein controlling the one or more flow control devices comprises actuating one or more actuators to move at least a portion of the first wall into the primary airflow.

[0130]The method of any preceding clause, wherein the engine further comprises one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, and wherein the method further comprises: controlling the one or more flow control devices to increase or decrease the flow rate proximate to a circumferential location of the one or more pipes based on the pressure or the flow rate.

[0131]The method of any preceding clause, wherein the inner casing comprises a first wall and a second wall defining the bleed air channel, and wherein controlling the one or more flow control devices comprises actuating one or more actuators to move at least a portion of the first wall into the bleed air channel.

[0132]A method for operating an aircraft, the aircraft comprising a fuselage, a wing attached to the fuselage, and an engine, the engine comprising a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity, the method comprising: detecting at least one of a pressure within the bleed air cavity or a flow rate of the bleed airflow within the bleed air cavity; and controlling one or more flow control devices to circumferentially balance a flow of the bleed airflow into the bleed air cavity or within the bleed air cavity based on the pressure or the flow rate.

[0133]A method for operating an aircraft, the aircraft comprising a fuselage, a wing attached to the fuselage, and an engine, the engine comprising a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity, and one or more pipes coupled to the outer casing and fluidly connected to the bleed air cavity, the method comprising: operating the engine during a takeoff flight phase of the aircraft; and while operating the engine during the takeoff flight phase of the aircraft, controlling one or more flow control devices to decrease a flow rate of the bleed airflow proximate to a circumferential location of the one or more pipes.

[0134]The method of any preceding clause, further comprising: operating the engine during a cruise flight phase of the aircraft; and while operating the engine during the cruise flight phase of the aircraft, controlling the one or more flow control devices to increase the flow rate of the bleed airflow proximate to the circumferential location of the one or more pipes.

[0135]An engine, comprising: a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity, and wherein the bleed air channel comprises an inlet end located proximate to the primary flow path and an outlet end disposed proximate to the bleed air cavity and distal to the inlet end; and one or more flow control devices located circumferentially about the compressor to actively or passively circumferentially balance a flow of the bleed airflow into the bleed air cavity or within the bleed air cavity, wherein the one or more flow control devices are disposed at least partially at the inlet end, at the outlet end, or between the inlet end and the outlet end.

[0136]The engine of any preceding clause, wherein the one or more flow control devices comprise one or more baffles having one or more apertures, wherein a size of the one or more apertures varies based on a circumferential location of the respective one or more apertures.

[0137]The engine of any preceding clause, wherein the one or more flow control devices comprise: one or more first baffles; and one or more second baffles; and wherein at least one of the one or more first baffles or the one or more second baffles comprises one or more apertures, and wherein at least one of the one or more first baffles or the one or more second baffles is movable.

[0138]The engine of any preceding clause, wherein the one or more flow control devices comprise one or more baffles having a first material and a second material, wherein a coefficient of thermal expansion of the first material is greater than a coefficient of thermal expansion of the second material.

[0139]An engine, comprising: a compressor including an inner casing and an outer casing, the inner casing defining a primary flow path for a primary airflow through the compressor, the inner casing and the outer casing defining a bleed air cavity therebetween, the inner casing at least partially defining a bleed air channel extending circumferentially about the inner casing between the primary flow path and the bleed air cavity to direct a bleed airflow from the primary airflow into the bleed air cavity, and wherein the bleed air channel comprises an inlet end located proximate to the primary flow path and an outlet end disposed proximate to the bleed air cavity and distal to the inlet end; and one or more flow control devices located circumferentially about the compressor to actively or passively circumferentially balance a flow of the bleed airflow into the bleed air cavity or within the bleed air cavity, wherein at least a portion of the one or more flow control devices extends axially aft from the outlet end into the bleed air cavity.

[0140]The engine of any preceding clause, wherein at least another portion of the one or more flow control devices extends radially outward with respect to the outlet end.

[0141]The engine of any preceding clause, further comprising at least one pipe fluidly coupled to the outer casing at a circumferential location to route the bleed airflow from the bleed air cavity to one or more downstream locations, and wherein the one or more flow control devices have a length in an aft axial direction that varies based on the circumferential location of the at least one pipe.

[0142]The method of any preceding clause, wherein the one or more flow control devices comprise one or more baffles having a first material and a second material, wherein a coefficient of thermal expansion of the first material is greater than a coefficient of thermal expansion of the second material.