COMBUSTOR HEAT SHIELD WITH MULTIPLE EFFUSION HOLE SIZES

BACKGROUND

[0001]The invention relates generally to a combustor of a gas turbine engine and, more particularly, to a combustor having improved cooling.

[0002]Cooling of combustor walls can be achieved by directing cooling fluid through holes in the combustor wall to provide effusion and/or film cooling. These holes may be provided as effusion cooling holes formed directly through the combustor wall and/or through a sheet metal heat shield of the combustor walls. Opportunities for improvement are continuously sought, however, to provide improved cooling, better mixing of the cooling air, better fuel efficiency and improved performance, all while reducing costs.

[0003]Further, known cooling designs are difficult to adapt to very small turbofan gas turbine engines since larger combustor designs cannot be scaled-down, since many physical parameters do not scale linearly, or at all, with size (droplet size, drag coefficients, manufacturing tolerances, etc.). Accordingly, there is a continuing need for improvements in gas turbine engine combustor design.

SUMMARY

[0004]A component having an effusion cooled surface, according to an example of this disclosure, includes a wall bound by an inner surface and an outer surface spaced from the inner surface in which the inner surface is configured to bound at least a portion of an interior region. The component further includes first effusion passages extending through the wall within a first zone of the wall and second effusion passages extending through the wall within a second zone discrete from the first zone. The diameters and density of the first effusion passages are greater than diameters and density of the second effusion passages.

[0005]According to a further example, the component is a heat shield bounding at least a portion of the combustion chamber of a combustor in which the heat shield defines a segment of a heat shield assembly or a continuous wall circumscribing an axis of the combustor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is an example gas turbine engine that includes a combustor.

[0007]FIG. 2 is a cross-section of an example combustor for the gas turbine engine that includes a heat shield.

[0008]FIG. 3 is a developed plan view of the example heat shield of the combustor.

[0009]FIG. 4 is a cross-sectional view through effusion holes within a first region of the heat shield.

[0010]FIG. 5 is a cross-sectional view through effusion holes within a second region of the heat shield.

DETAILED DESCRIPTION

[0011]A disclosed herein is an effusion hole configuration for a combustor wall, a heat shield for a combustor, or any other effusion-cooled surface of a component in which physical geometry of the component hinders or prevents the requisite number of effusion holes for a target mass flow of effusion cooling across the surface. Operational conditions of the combustor wall, combustor heat shield, and/or other effusion-cooled wall can be associated with a minimum inter-passage thickness and/or a flow split between effusion cooling and back side cooling features to maintain acceptable thermal and mechanical performance of the component. The component can include one or more obstructions such as mechanical attachment features, openings for components that penetrate the wall and/or heat shield, and/or dilution holes that geometrically limit potential effusion hole configurations. Further, effusion holes can form acute angles with the effusion-cooled surface and can be arranged at various orientations with respect to adjacent effusion holes, further limiting the number of effusion holes extending through a zone of the heat shield, combustor wall, and/or other effusion-cooled surface. In these instances, providing a mass flow of effusion cooling along the component surface to meet the operational and optimal conditions can be hindered by the component geometry.

[0012]The effusion hole configuration disclosed herein includes at least two regions of the component surface in which diameters of effusion holes within the first region are larger than diameters of effusion holes within the second region. This enables the effusion cooling of the combustor wall, combustor heat shield, or other effusion-cooled wall to deliver relatively less mass-flow per effusion hole across a larger surface area in the second region while delivering relatively more mass-flow within a geometrically limited first region. While the following disclosure describes the effusion hole configuration in relation to a combustor heat shield, features of the effusion hole configuration can be applied to other effusion-cooled component surfaces in other examples.

[0013]FIG. 1 is an axial cross-section through an example gas turbine engine 10 that includes combustor 12 equipped with heat shield 14, which can be formed by an assembly of wall segments or by a continuous wall circumscribing an axis of gas turbine engine 10. While gas turbine engine 10 is depicted as a turbofan engine, heat shield 14 can be incorporated into combustors of other types of gas turbine engine and/or other types of combustors. In some examples, gas turbine engine 10 can be a turboshaft engine or a turboprop engine suitable for propulsion of an aircraft and/or suitable to power an auxiliary system of the aircraft (e.g., an auxiliary power unit). In other examples, gas turbine engine 10 can be a ground-based industrial gas turbine engine or an aeroderivative gas turbine engine. Further, gas turbine engine 10 can include fewer or more compressor stages and/or turbine stages than the number of stages depicted by FIG. 1 and said stages can be configured as axial compressors and/or turbines, or centrifugal compressors and/or turbines arranged to form fewer or more shaft spools than the configuration depicted in FIG. 1.

[0014]As depicted in FIG. 1, gas turbine engine 10 includes inlet 16, fan 18, fan case 20, bypass duct 22, low-pressure axial compressor 24, high-pressure centrifugal compressor 26, diffuser 28, plenum 30, combustor 12, fuel tubes 32, nozzle guide vane 34, turbines 36, and exhaust nozzle 38. Air intake into gas turbine engine 10 through inlet 16 passes over fan 18 in fan case 20 and is then split into an outer annular flow through the bypass duct 22 and an inner flow through the low-pressure axial compressor 24 and high-pressure centrifugal compressor 26. Compressed air exits high-pressure centrifugal compressor 26 through diffuser 28 and is contained within plenum 30 that surrounds combustor 12. Fuel supplied to combustor 12 through fuel tubes 32 mixes with air supplied from plenum 30 when sprayed through nozzles into combustor 12 as a fuel air mixture and is ignited. A portion of the compressed air within plenum 30 is admitted into combustor 12 through orifices in the side walls to create a cooling air film along the combustor walls and/or heat shields, or is used for cooling, which eventually mixes with the hot gases from combustor 12 and passes over nozzle guide vane 34 and turbines 36 before exiting nozzle 38 as exhaust. It will be understood that the foregoing description is intended to be exemplary of only one of many possible configurations of engine suitable for incorporation of the effusion hole configuration as described in reference to heat shield 14.

[0015]FIG. 2 is an axial cross-section of combustor 12 with inner wall 40, outer wall 42, head wall 44 (collectively heat shield 14). Inner wall 40 is spaced radially inward from outer wall 42 relative to axis C to form annular combustion chamber 46. Head wall 44 extends from inner wall 40 to outer wall 42 to enclose an upstream end of combustor 12. Fuel tube 32 communicates with combustion chamber 46 via a port extending through head wall 44, however, the fuel nozzle arrangement is not shown, for simplicity. An ignitor extends through a port of outer wall 42 and is positioned in relation to one or more fuel tubes 32 to initiate combustion within combustion chamber 46.

[0016]FIG. 3 is a developed plan view of an example heat shield 14 of combustor 12. As depicted, heat shield 14 corresponds to a region of combustor that includes dilution holes 48. However, in other examples, heat shield 14 can be representative of a heat shield in the primary combustion zone of combustor 12 and/or a downstream region of combustor 12 between the primary combustion zone and turbine 36. Heat shield 14 includes at least two zones having effusion holes with different diameters. In other examples, heat shield 14 can include more than two zones, at least two zones having effusion holes with different diameters. In yet other examples, heat shield 14 can include more than two zones, each zone having effusion holes with different diameters.

[0017]In the depicted example, heat shield 14 is a heat shield segment bound by inner surface 50, outer surface 52, upstream surface 54, downstream surface 56, and circumferential surfaces 58. In other examples, heat shield 14 can be a continuous wall that circumscribes an axis of combustor 12 and/or gas turbine engine 10. Combustion products flow through combustor 12 from upstream surface 54 towards downstream surface 56 as indicated by arrow F, representing an overall flow direction within combustor 12. Upstream surface 54, downstream surface 56, and/or circumferential surfaces 58 can be spaced from adjacent heat shield segments as represented by dashed lines 60 to accommodate thermal growth during operation of combustor 12. Inner surface 50 faces inward toward combustion chamber 46 while outer surface 52 faces radially outward from combustor chamber 46 as shown in FIG. 2 such that inner surface 50 of heat shield 14 forms at least a partial boundary of the combustion chamber.

[0018]Heat shield 14 includes at least first zone 62 and second zone 64, each zone discrete from the other zones such that no zone overlaps with any other zone of heat shield 14. First zone 62 and second zone 64, as depicted in FIG. 3, is an example zone configuration for heat shield 14. Dashed line Z demarks the division between first zone 62 and second zone 64. First zone 62 extends between dash line Z, upstream surface 54, and portions of circumferential surfaces 58. Second zone 64 extends between dashed line Z, downstream surface 56, and portions of circumferential surfaces 58. Heat shield 14 can include at least one obstruction within first zone 62 and/or second zone 64, which in this instance includes dilution holes 48 and regions R in which heat shield 14 includes mechanical attachments (e.g., one or more studs 66 shown in dashed lines) extending from outer surface 52 towards walls of combustor 12.

[0019]Effusion holes 68 extend through heat shield 14 from outer surface 52 to inner surface 50. First group 68A of effusion holes 68 intersect inner surface 50 within first zone 62, and second group 68B of effusion holes 68 intersect inner surface 50 within second zone 64. First diameters D1 of effusion holes 68 within group 68A are larger than second diameters D2 of effusion holes 68 within group 68B. Spacing S1 at inner surface 50 between effusion holes 68 within group 68A can be equal to or less than spacing S2 at inner surface 50 between effusion holes 68 within group 68B. Collectively, effusion holes 68 within group 68A and within group 68B are each configured to deliver a target mass flow of effusion cooling fluid along inner surface 50 within first zone 62 and second zone 64 respectively.

[0020]Since diameters of effusion holes 68 within first zone 62 exceed diameter of effusion holes with in second zone 64 while having equal to or less spacing between adjacent holes, the percent open area of effusion holes 68 within first zone 62 is greater than percent open area of effusion holes 68 within second zone 64. In some examples, the percent open area of effusion holes within first zone 62 is at least 1.25 times the percent open area of effusion holes in second zone 64. In another example, the percent open area of effusion holes within first zone 62 is at least 1.50 times the percent open area of effusion holes in second zone 64. In yet another example, the percent open area of effusion holes within first zone 62 is at least 2.00 times the percent open area of effusion holes in second zone 64. In each of the foregoing examples, the percent open area of effusion holes within first zone 62 can be no more than 3.00 times the percent open area of effusion holes in second zone 64, and the percent open area of effusion holes in first zone 62 can be any multiple between 1.25 times and 3.00 times the percent open area of effusion holes in second zone 64.

[0021]Similarly, the density of effusion holes 68 within first zone 62 can exceed a density of effusion holes 68 within second zone 64. For example, the number of effusion holes per unit surface area of inner surface 50 within first zone 62 can be at least 1.25 times the number of effusion holes per unit surface area of inner surface 50 within second zone 64. In another example, the number of effusion holes per unit surface area of inner surface 50 within first zone 62 can be at least 1.50 times the number of effusion holes per unit surface area of inner surface 50 within second zone 64. In yet another example, the number of effusion holes per unit surface area of inner surface 50 within first zone 62 can be at least 1.75 times the number of effusion holes per unit surface area of inner surface 50 within second zone 64. In each of the foregoing examples, the number of effusion holes within first zone 62 can be any multiple between 1.25 times and 2.50 times the number of effusion holes in second zone 64.

[0022]FIG. 4 is a cross-sectional view through heat shield 14 representative of effusion holes 68 within first zone 62 of inner surface 50. Inner surface 50, outer surface 52, and effusion holes 68 within group 68A, each having diameter D1 are shown. Effusion holes 68 are inclined relative to inner surface 50 such that inclination angle A is formed between centerline of each effusion hole 68 and inner surface 50 at an exit thereof. Inclination angle A can be an acute angle greater than or equal to 5 degrees and less than or equal to 40 degrees in some examples, or greater than or equal to 10 degrees and less than or equal to 30 degrees in other examples. In other examples of heat shield 14, inclination angle can be perpendicular to inner surface 50 at an exit of effusion hole 68, or any value between 5 degrees and 90 degrees. While inclination angle A of each effusion hole 68 is shown to be equal in the depicted example, inclination angle A can be different for some, or for each effusion hole 68 within first zone 62 and/or within second zone 64. Moreover, inclination angle A is depicted within a cross-sectional plane, which can be representative of any orientation of effusion hole 68 with respect to inner surface 50 heat shield including discharge directions orientated in an upstream direction, a downstream direction, a circumferential direction, and combinations thereof relative to flow direction F depicted in FIG. 3. Effusion holes 68 within first zone 62 are spaced at least distance S1 with respect to adjacent effusion holes 68 as shown to maintain sufficient material between effusion holes 68 in view of operational conditions of heat shield 14. Distance S1 is less than or equal to distance S2 of effusion holes 68 within second zone 64. In some examples, first zone 62 may coincide with a region of combustor with higher heat flux into heat shield 14 relative to heat flux into heat shield 14 within second zone 64.

[0023]FIG. 5 is a cross-sectional view through heat shield 14 representative of effusion holes 68 within second zone 64 of inner surface 50. Inner surface 50, outer surface 52, and effusion holes 68 within group 68B, each having diameter D2 are shown. Effusion holes 68 are inclined relative to inner surface 50 by inclination angle A in the same manner as holes within first zone 62, and can include a variation of inclination angles A described in reference to FIG. 4. Effusion holes 68 within second zone 64 are spaced a distance d2 with respect to adjacent effusion holes 68 as shown to maintain sufficient material between effusion holes 68 in view of operational conditions of heat shield 14. In some examples, second zone 64 may coincide with a region of combustor with lower heat flux into heat shield 14 relative to heat flux into heat shield 14 within first zone 62.

Discussion of Possible Embodiments

[0024]The following are non-exclusive descriptions of possible embodiments of the present invention.

A Component with an Effusion-Cooled Surface

[0025]A component according to an example embodiment of this disclosure includes, among other possible things, a wall bound by an inner surface and an outer surface spaced from the inner surface. The inner surface configured to bound at least a portion of an interior region. The component further includes a plurality of first effusion holes extending through the wall from the outer surface to the inner surface within a first zone of the wall and a plurality of second effusion holes extending through the wall from the outer surface to the inner surface within a second zone of the wall discrete from the first zone. The first diameter of each first effusion hole is larger than a second diameter of each of the second effusion holes. The first density of the plurality of first effusion holes along the inner surface is greater than a second density of the plurality of second effusion holes along the inner surface.

[0026]The component of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components.

[0027]A further embodiment of the foregoing component, wherein the first density can be greater than 1.25 times the second density.

[0028]A further embodiment of any of the foregoing components, wherein the first density can be greater than 1.50 times the second density.

[0029]A further embodiment of any of the foregoing components, wherein the first density can be greater than 2.00 times the second density.

[0030]A further embodiment of any of the foregoing components, wherein the first density can be less than or equal to 3.00 times the second density.

[0031]A further embodiment of any of the foregoing components, wherein a first percent open area of the plurality of first effusion holes can be at least 1.25 times a second percent open area of the plurality of second effusion holes.

[0032]A further embodiment of any of the foregoing components, wherein the first zone can include at least one obstruction feature spaced from each first effusion hole, each first effusion hole extending through the heat shield apart from the obstruction.

[0033]A further embodiment of any of the foregoing components, wherein the first diameter can be at least 1.10 times the second diameter.

[0034]A further embodiment of any of the foregoing components, wherein the wall can form a segment of the heat shield, extending circumferentially from a first side to a second side to subtend a sector relative to an axis, and extending axially from a first end to a second end parallel to the axis.

[0035]A further embodiment of any of the foregoing components, wherein the inner surface can be axisymmetric about an axis and configured to bound at least a portion of the interior region.

[0036]A further embodiment of any of the foregoing components can further include further a stud extending outward from the outer surface of the wall.

[0037]A further embodiment of any of the foregoing components, wherein a stud region of the inner surface coinciding with the stud is devoid of first effusion holes and second effusion holes.

[0038]A further embodiment of any of the foregoing components, wherein the component can be a heat shield, and wherein the interior region can be a combustion chamber such that the inner surface bounds at least a portion of the combustion chamber.

[0039]While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.