Patent Publication Number: US-11391461-B2

Title: Combustor bulkhead with circular impingement hole pattern

Description:
BACKGROUND 
     1. Technical Field 
     This disclosure relates generally to combustors for gas turbine engines, and more particularly to cooling of heat shields for use in a combustor. 
     2. Background Information 
     Combustors, such as those used in gas turbine engines, may generally include radially spaced inner and outer shells which define a combustion chamber therebetween. A bulkhead may be provided at the forward end of the combustion chamber to shield a forward section of the combustor from the relatively high temperatures in the combustion chamber. A heat shield including one or more heat shield panels may be mounted on the bulkhead for further heat protection. Typically, relatively cool air from outside of the combustor is used to cool the bulkhead side of the heat shield panels. This cooling air may then be directed into the combustion chamber through effusion holes in the heat shield extending between the bulkhead side and the combustion chamber side. 
     However, in an attempt to improve flame anchoring within the combustor, modern heat shield panels may not contain large amounts of effusion holes. Due to the nature of hot gas recirculation near the heat shield, the lack of effusion cooling holes in the heat shield panels may result in significantly increased heat shield temperatures. This high-temperature effect on the heat shield can be particularly aggravated in proximity to low-flow cavity regions disposed between the heat shield and the combustor shells. 
     Impingement cooling holes have been used in bulkheads to direct cooling air so as to impinge on the heat shield panel, cooling the panel. Conventionally, impingement cooling hole density has been biased towards hot spots known to exist in the heat shield panels during operation of the combustor. However, such a configuration may result in non-uniform, and therefore sub-optimal, cooling flow between the bulkhead and heat shield panels as well as dead spots which can result in elevated temperatures as well as collections of dirt/debris which are not effectively removed by the cooling air. Accordingly, what is needed are improvements to heat shield panel cooling addressing one or more of the above-noted concerns. 
     SUMMARY 
     It should be understood that any or all of the features or embodiments described herein can be used or combined in any combination with each and every other feature or embodiment described herein unless expressly noted otherwise. 
     According to an embodiment of the present disclosure, a combustor for a gas turbine engine includes a combustion chamber defined between an inner shell and an outer shell. The combustor further includes a bulkhead extending between the inner shell and the outer shell. The bulkhead includes a plurality of impingement cooling rings. Each impingement cooling ring of the plurality of impingement cooling rings includes a plurality of impingement cooling holes extending through the bulkhead. The combustor further includes a heat shield panel including a first surface facing the combustion chamber and a second surface opposite the first surface and facing the bulkhead. The heat shield panel is mounted to the bulkhead so as to define an impingement cooling chamber between the bulkhead and the heat shield panel. The heat shield panel further includes a perimeter and an opening extending through the heat shield panel between the first surface and the second surface. The opening is centered about an opening center axis. The heat shield panel further includes a radial portion between the perimeter and the opening, with respect to the opening center axis, which is free of penetrations. The plurality of impingement cooling holes of each of the plurality of impingement cooling rings are directed toward the radial portion of the heat shield panel. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of impingement cooling rings are concentrically disposed about the opening center axis. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of impingement cooling rings are radially spaced such that a first radial distance between adjacent impingement cooling rings of the plurality of impingement cooling rings decreases as a second radial distance from the opening center axis increases. 
     In the alternative or additionally thereto, in the foregoing embodiment, a first plurality of impingement cooling holes of a first impingement cooling right of the plurality of impingement cooling rings is offset with respect to a second plurality of impingement cooling holes of an adjacent second impingement cooling ring of the plurality of impingement cooling rings. 
     In the alternative or additionally thereto, in the foregoing embodiment, the second impingement cooling ring is radially outside the first impingement cooling ring, with respect to the opening center axis, and the second plurality of impingement cooling holes includes a greater number of impingement cooling holes than the first plurality of impingement cooling holes. 
     In the alternative or additionally thereto, in the foregoing embodiment, the heat shield panel includes a first plurality of effusion holes extending through the heat shield panel and disposed radially between the radial portion and the opening with respect to the opening center axis. 
     In the alternative or additionally thereto, in the foregoing embodiment, the heat shield panel further includes a second plurality of effusion holes extending through the heat shield panel and disposed radially between the radial portion and the perimeter with respect to the opening center axis. 
     In the alternative or additionally thereto, in the foregoing embodiment, effusion holes of the first plurality of effusion holes have a greater diameter than effusion holes of the second plurality of effusion holes. 
     In the alternative or additionally thereto, in the foregoing embodiment, the radial portion has a first radial length in a direction between an inner diameter position of the opening and an outer diameter position of the perimeter which is greater than 70 percent of a second radial length between the inner diameter position of the opening and the outer diameter position of the perimeter. 
     In the alternative or additionally thereto, in the foregoing embodiment, each of the plurality of impingement cooling holes of the plurality of impingement cooling rings are oriented normal to a surface of the bulkhead facing the heat shield panel. 
     In the alternative or additionally thereto, in the foregoing embodiment, the radial portion of the heat shield panel includes a plurality of pin fins extending from the heat shield panel towards the bulkhead. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of pin fins has a pin fin height that is between 70 percent and 85 percent of a height of the impingement cooling chamber. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of impingement cooling rings includes at least five impingement cooling rings. 
     According to another embodiment of the present disclosure, a method for cooling a combustor heat shield panel of a gas turbine engine is disclosed. The method includes providing a bulkhead extending between an inner shell and an outer shell. The inner shell and the outer shell define a combustion chamber therebetween. The bulkhead includes a plurality of impingement cooling rings. Each impingement cooling ring includes a plurality of impingement cooling holes extending through the bulkhead. The method further includes providing a heat shield including a first surface facing the combustion chamber and a second surface opposite the first surface and facing the bulkhead. The heat shield panel mounted to the bulkhead so as to define an impingement cooling chamber between the bulkhead and the heat shield panel. The heat shield panel further including a perimeter and an opening extending through the heat shield panel between the first surface and the second surface. The opening centered about an opening center axis. The heat shield panel further including a radial portion between the perimeter and the opening, with respect to the opening center axis, which is free of penetrations. The method further includes directing an impingement cooling flow toward the radial portion of the heat shield panel with the plurality of impingement cooling holes of each of the plurality of impingement cooling rings. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of impingement cooling rings are concentrically disposed about the opening center axis. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of impingement cooling rings are radially spaced such that a first radial distance between adjacent impingement cooling rings of the plurality of impingement cooling rings decreases as a second radial distance from the opening center axis increases. 
     In the alternative or additionally thereto, in the foregoing embodiment, the method further includes directing a first effusion cooling flow with a first plurality of effusion holes extending through the heat shield panel and disposed radially between the radial portion and the opening with respect to the opening center axis and directing a second effusion cooling flow with a second plurality of effusion holes extending through the heat shield panel and disposed radially between the radial portion and the perimeter with respect to the opening center axis. 
     In the alternative or additionally thereto, in the foregoing embodiment, the radial portion of the heat shield panel includes a plurality of pin fins extending from the heat shield panel towards the bulkhead. 
     In the alternative or additionally thereto, in the foregoing embodiment, the plurality of pin fins has a pin fin height that is between 70 percent and 85 percent of a height of the impingement cooling chamber. 
     According to another embodiment of the present disclosure, a combustor for a gas turbine engine includes a combustion chamber defined between an inner shell and an outer shell. The combustor further includes a bulkhead extending between the inner shell and the outer shell. The bulkhead includes a plurality of impingement cooling rings. Each impingement cooling ring of the plurality of impingement cooling rings includes a plurality of impingement cooling holes extending through the bulkhead. The combustor further includes a heat shield panel including a first surface facing the combustion chamber and a second surface opposite the first surface and facing the bulkhead. The heat shield panel is mounted to the bulkhead so as to define an impingement cooling chamber between the bulkhead and the heat shield panel. The heat shield panel further includes a perimeter and an opening extending through the heat shield panel between the first surface and the second surface. The opening is centered about an opening center axis. The heat shield panel further including a radial portion between the perimeter and the opening, with respect to the opening center axis, which is free of penetrations. The radial portion of the heat shield panel including a plurality of pin fins extending from the heat shield panel towards the bulkhead. The plurality of impingement cooling rings are concentrically disposed about the opening center axis and radially spaced such that a first radial distance between adjacent impingement cooling rings of the plurality of impingement cooling rings decreases as a second radial distance from the opening center axis increases. A second impingement cooling ring of the plurality of impingement cooling rings, including a second plurality of impingement cooling holes, is radially outside a first impingement cooling ring of the plurality of impingement cooling rings, including a first plurality of impingement cooling holes, and the second plurality of impingement cooling holes includes a greater number of impingement cooling holes than the first plurality of impingement cooling holes. The plurality of impingement cooling holes of each of the plurality of impingement cooling rings are directed toward the radial portion of the heat shield panel. 
     The present disclosure, and all its aspects, embodiments and advantages associated therewith will become more readily apparent in view of the detailed description provided below, including the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a side cross-sectional view of a gas turbine engine in accordance with one or more embodiments of the present disclosure. 
         FIG. 2  illustrates a cross-sectional view of an exemplary combustor of a gas turbine engine in accordance with one or more embodiments of the present disclosure. 
         FIG. 3  illustrates a side view of a portion of a bulkhead of the combustor of  FIG. 2  in accordance with one or more embodiments of the present disclosure. 
         FIG. 4A  illustrates a portion of the bulkhead of  FIG. 3  in accordance with one or more embodiments of the present disclosure. 
         FIG. 4B  illustrates a portion of the bulkhead of  FIG. 3  in accordance with one or more embodiments of the present disclosure. 
         FIG. 5  illustrates a perspective view of a heat shield panel of the combustor of  FIG. 2  in accordance with one or more embodiments of the present disclosure. 
         FIG. 6  illustrates a side view of the heat shield panel of  FIG. 5  from a cold-side perspective in accordance with one or more embodiments of the present disclosure. 
         FIG. 7  illustrates another side view of the heat shield panel of  FIG. 5  from a cold-side perspective in accordance with one or more embodiments of the present disclosure. 
         FIG. 8  illustrates a cross-sectional view of the heat shield panel of  FIG. 7  in accordance with one or more embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It is noted that various connections are set forth between elements in the following description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. It is further noted that various method or process steps for embodiments of the present disclosure are described in the following description and drawings. The description may present the method and/or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation. 
     Referring to  FIG. 1 , an exemplary gas turbine engine  10  is schematically illustrated. The gas turbine engine  10  is disclosed herein as a two-spool turbofan engine that generally includes a fan section  12 , a compressor section  14 , a combustor section  16 , and a turbine section  18 . The fan section  12  drives air along a bypass flowpath  20  while the compressor section  14  drives air along a core flowpath  22  for compression and communication into the combustor section  16  and then expansion through the turbine section  18 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiments, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including those with three-spool architectures. 
     The gas turbine engine  10  generally includes a low-pressure spool  24  and a high-pressure spool  26  mounted for rotation about a longitudinal centerline  28  of the gas turbine engine  10  relative to an engine static structure  30  via one or more bearing systems  32 . It should be understood that various bearing systems  32  at various locations may alternatively or additionally be provided. 
     The low-pressure spool  24  generally includes a first shaft  34  that interconnects a fan  36 , a low-pressure compressor  38 , and a low-pressure turbine  40 . The first shaft  34  may be connected to the fan  36  through a gear assembly of a fan drive gear system  42  to drive the fan  36  at a lower speed than the low-pressure spool  24 . The high-pressure spool  26  generally includes a second shaft  44  that interconnects a high-pressure compressor  46  and a high-pressure turbine  48 . It is to be understood that “low pressure” and “high pressure” or variations thereof as used herein are relative terms indicating that the high pressure is greater than the low pressure. An annular combustor  50  is disposed between the high-pressure compressor  46  and the high-pressure turbine  48  along the longitudinal centerline  28 . The first shaft  34  and the second shaft  44  are concentric and rotate via the one or more bearing systems  32  about the longitudinal centerline  28  which is collinear with respective longitudinal centerlines of the first and second shafts  34 ,  44 . 
     Airflow along the core flowpath  22  is compressed by the low-pressure compressor  38 , then the high-pressure compressor  46 , mixed and burned with fuel in the combustor  50 , and then expanded over the high-pressure turbine  48  and the low-pressure turbine  40 . The low-pressure turbine  40  and the high-pressure turbine  48  rotationally drive the low-pressure spool  24  and the high-pressure spool  26 , respectively, in response to the expansion. 
     Referring to  FIG. 2 , the combustor  50  includes an annular outer shell  52  and an annular inner shell  54  spaced radially inward of the outer shell  52 , thus defining an annular combustion chamber  56  therebetween. An annular hood  58  is positioned axially forward of the outer shell  52  and the inner shell  54  and spans between and sealably connects to respective forward ends of the outer shell  52  and the inner shell  54 . It should be understood that relative positional terms, such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are relative to the normal operational attitude of the gas turbine engine  10  and should not be considered otherwise limiting. 
     The combustor  50  may include one or more liner panels  60  mounted to and spaced away from one or both of the outer shell  52  and the inner shell  54 . The liner panel  60  may include a first surface  62  facing the combustion chamber  56  and a second surface  64  opposite the first surface  62 . The second surface  64  of the liner panel  60  may be spaced from the respective shell  52 ,  54  so as to define a liner cooling chamber  66  therebetween. 
     Referring to  FIGS. 2-8 , the combustor  50  includes a bulkhead  68  having a first surface  70  facing the combustion chamber  56  and a second surface  72  opposite the first surface  70 . The bulkhead  68  further includes an outer radial end  74  and an inner radial end  76  opposite the outer radial end  74 . The bulkhead  68  may be connected to and extend between the outer shell  52  and the inner shell  54 . For example, the bulkhead  68  may be connected to the outer shell  52  at the outer radial end  74  while the bulkhead  68  may be connected to the inner shell  54  at the inner radial end  76 . The bulkhead  68  divides the combustion chamber  56  and a hood chamber  78  (i.e., the combustion chamber  56  is disposed downstream of the bulkhead  68  while the hood chamber  78  is disposed upstream of the bulkhead  68 ). The bulkhead  68  includes an annular heat shield  80  mounted to the first surface  70  of the bulkhead  68  and generally serving to thermally protect the bulkhead  68  and forward portions of the combustor  50 , such as the hood chamber  78 . 
     The heat shield  80  includes one or more heat shield panels  82 . The heat shield panel  82  may include a first surface  84  facing the combustion chamber  56  and a second surface  86  opposite the first surface  84 , an outer circumferential side  88  and an inner circumferential side  90  opposite the outer circumferential side  88 , and a first radially extending side  92  and a second radially extending side  94  opposite the first radially extending side  92 . Each of the first radially extending side  92  and the second radially extending side  94  may extend radially between the outer circumferential side  88  and the inner circumferential side  90 . The outer circumferential side  88 , the inner circumferential side  90 , the first radially extending side  92 , and the second radially extending side  94  form a perimeter of the heat shield panel  82 . 
     The bulkhead  68  includes at least one opening  96  extending through bulkhead  68  between the combustion chamber  56  and the hood chamber  78 . Each opening of the at least one opening  96  may accommodate a respective fuel injector (not shown) extending through the respective opening of the at least one opening  96  from the hood chamber  78  into the combustion chamber  56 . The fuel injector may be configured to provide a mixture of fuel, air, and/or additional fluids for combustion in the combustion chamber  56 . Similarly, the heat shield panel  82  may include an opening  98  corresponding to and aligned with a respective opening of the at least one opening  96  of the bulkhead  68 . The opening  98  extends through the heat shield panel  82  between the first surface  84  and the second surface  86 . The opening  98  of the heat shield panel  82  is centered about an opening center axis  100 . In various embodiments, the respective opening of the at least one opening  96  of the bulkhead  68  may also be centered about the opening center axis  100 . 
     The heat shield panel  82  may include a wall  102  extending from the second surface  86  of the heat shield panel  82  toward the bulkhead  68 . The wall  102  may extend around all or a portion of the perimeter of the heat shield panel  82 . All or a portion of the wall  102  may contact the first surface  70  of the bulkhead  68  and may form a seal between the bulkhead  68  and the heat shield panel  82 . The first surface  70  of the bulkhead  68  and the second surface  86  of the heat shield panel  82  may defined an impingement cooling chamber  104  therebetween. The heat shield panel  82  may further include a wall  106  extending from the second surface  86  of the heat shield panel  82  toward the bulkhead  68  around all or a portion of the opening  98 . All or a portion of the wall  106  may contact the first surface  70  of the bulkhead  68  and may form a seal between the bulkhead  68  and the heat shield panel  82  further defining the impingement cooling chamber  104 . 
     In various embodiments, the heat shield panel  82  may include one or more rails  108  extending from the second surface  86  of the heat shield panel  82  toward the bulkhead  68 . The one or more rails  108  may contact the first surface  70  of the bulkhead  68  and may form a seal between the bulkhead  68  and the heat shield panel  82 . Accordingly, the one or more rails  108  may subdivide the impingement cooling chamber  104  into a plurality of impingement cooling chambers. The heat shield panel  82  may further include one or more studs  110  projecting from the second surface  86  of the heat shield panel  82  for mounting the heat shield panel  82  to the bulkhead  68 . 
     To cool the heat shield panel  74 , an impingement cooling flow  112  of relatively cool air from outside the combustor  50  (e.g., from the hood chamber  78 ) is directed to the second surface  86  of the heat shield panel  82 , thereby cooling the heat shield panel  82  (see, e.g.,  FIG. 6  illustrating the locations of impingement of the impingement cooling flow  112  on the second surface  86  of the heat shield panel  82 ). Accordingly, the bulkhead  68  of the present disclosure includes a plurality of impingement cooling rings  114  disposed about a respective opening of the at least one opening  96  of the bulkhead  68 . Each impingement cooling ring of the plurality of impingement cooling rings  114  includes a plurality of impingement cooling holes  116  extending through the bulkhead  68  between the first surface  70  and the second surface  72 . The plurality of impingement cooling holes  116  of the plurality of impingement cooling rings  114  may be oriented normal to the first surface  70  of the bulkhead  68  facing the heat shield panel  82 . One or more of the at least one opening  96  of the bulkhead  68  may have a respective plurality of impingement cooling rings  114  disposed about the one or more of the at least one opening  96 . In various embodiments, the bulkhead  68  may include impingement cooling holes which are not part of the impingement cooling rings of the plurality of impingement cooling rings  114 . In various embodiments, the plurality of impingement cooling rings  114  may include at least five impingement cooling rings, however, a greater or lesser number of impingement cooling rings may be used. 
     The heat shield panel  82  includes a radial portion  118  of the heat shield panel  82  radially disposed between the perimeter of the heat shield panel  82  and the opening  98  with respect to the opening center axis  100 . The radial portion  118  of the heat shield panel  82  is free of penetrations (e.g., cooling holes or other apertures extending through the heat shield panel  82  within the radial portion  118  of the heat shield panel  82 ). For example, the radial portion  118  of the heat shield panel  82  does not include effusion holes for cooling of the heat shield panel  82 . The plurality of impingement cooling holes  116  of each of the plurality of impingement cooling rings  114  are directed toward the radial portion  118  of the heat shield panel  82  for impingement cooling thereof. Accordingly, the plurality of impingement cooling rings  114  may be radially aligned with the radial portion  118  of the heat shield panel  82  with respect to the opening center axis  100 . 
     Referring to  FIG. 5 , in various embodiments, the radial portion  118  is a substantial portion of the radial extent of the heat shield panel  82 . For example, the radial portion  118  may have a radial length L 1  in a direction between an inner diameter position ID of the opening  98  and an outer diameter position OD of the perimeter of the heat shield panel  82  which is greater than 50 percent of a radial length L 2  between the inner diameter position ID and the outer diameter position OD. In various other embodiments, the radial length L 1  may be greater than 70 percent of the radial length L 2 . In various embodiments, the radial portion  118  may circumferentially encompass the opening  98  of the heat shield panel  82  (i.e., the radial portion  118  may be radially disposed between the opening  98  and the perimeter of the heat shield panel  82  about the entire circumference of the opening  98 , with respect to the opening center axis  100 ). 
     Referring to  FIGS. 3-8 , in various embodiments, the plurality of impingement cooling rings  114  may be concentrically disposed about the opening center axis  100  (see, e.g.,  FIGS. 4A and 4B ). In various embodiments, the plurality of impingement cooling rings  114  may be radially spaced such that a radial distance D 1  between adjacent impingement cooling rings of the plurality of impingement cooling rings  114  may decrease as a radial distance D 2  from the opening center axis  100  increases (see, e.g.,  FIG. 4B ). For example, adjacent impingement cooling rings of the plurality of impingement cooling rings  114  may progressively be located radially closer to one another as a distance from the opening  98  increases. As will be discussed in greater detail, this configuration of the plurality of impingement cooling rings  114  may provide a more constant backpressure of the impingement cooling air passing through the impingement cooling chamber  104  along the radial extent of the impingement cooling chamber  104 . In various other embodiments, the plurality of impingement cooling rings  114  may have a constant radial spacing between adjacent impingement cooling rings of the plurality of impingement cooling rings  114  (see, e.g.,  FIG. 4A ). 
     In various embodiments, for example, a first plurality of impingement cooling holes of a first impingement cooling ring of the plurality of impingement cooling rings  114  may be offset with respect to a second plurality of impingement cooling holes of an adjacent second impingement cooling ring of the plurality of impingement cooling rings  114 . In other words, the plurality of impingement cooling holes of an impingement cooling ring may not be circumferentially aligned with the plurality of impingement cooling holes of an adjacent impingement cooling ring. This configuration of the plurality of impingement cooling rings  114  may reduce or eliminate the occurrence of dead spots within the impingement cooling chamber  104  (i.e., areas within the impingement cooling chamber  104  having reduced cooling flow) which may contribute to more uniform cooling flow as well as a reduction in dirt/debris accumulation within the impingement cooling chamber  104 . 
     In various embodiments, the plurality of impingement cooling holes  116  of each impingement cooling ring of the plurality of impingement cooling rings  114  may include a different number of impingement cooling holes with respect to one or more other impingement cooling rings of the plurality of impingement cooling rings  114 . In various embodiments, for example, a second plurality of impingement cooling holes of a second impingement cooling ring of the plurality of impingement cooling rings  114  may be disposed radially outside of a first plurality of impingement cooling holes of a first impingement cooling ring of the plurality of impingement cooling rings  114  with respect to the opening center axis  100 . The second plurality of impingement cooling holes may include a greater number of impingement cooling holes than the first plurality of impingement cooling holes. 
     The heat shield panel may include effusion holes outside of the radial portion  118  of the heat shield panel  82 . In various embodiments, the heat shield panel  82  may include a plurality of inner diameter effusion holes  120  extending through the heat shield panel  82  and disposed radially between the radial portion  118  and the opening  98  with respect to the opening center axis  100 . In various embodiments, the heat shield panel  82  may alternatively or additionally include a plurality of outer diameter effusion holes  122  extending through the heat shield panel  82  and disposed radially between the radial portion  118  and the perimeter of the heat shield panel  82  with respect to the opening center axis  100 . In various embodiments, the effusion holes of the plurality of inner diameter effusion holes  120  may have a greater diameter than the effusion holes of the plurality of outer diameter effusion holes  122 . Accordingly, in various embodiments, a significantly greater amount of the impingement cooling flow  112  entering the impingement cooling chamber  104  may exit the impingement cooling chamber  104  via the plurality of inner diameter effusion holes  120  than the plurality of outer diameter effusion holes  122 . As a result, cooling air flow within the impingement cooling chamber  104  may generally be in a direction from the perimeter of the heat shield panel  82  toward the plurality of inner diameter effusion holes  120 . 
     Referring to  FIGS. 7 and 8 , in various embodiments, the radial portion  118  of the heat shield panel  82  includes a plurality of pin fins  124  extending from the heat shield panel  82  towards the bulkhead  68 . In various embodiments, the plurality of pin fins  124  has a pin fin height H 1  that is between 70 percent and 85 percent of an impingement cooling chamber  104  height H 2 . In various other embodiments, the pin fin height H 1  is between 75 percent and 80 percent of the impingement cooling chamber height H 2 . In various embodiments, the plurality of pin fins  124  may additionally extend from portions of the heat shield panel  82  outside of the radial portion  118 . 
     Aspects of the present disclosure, such as the configuration of the plurality of impingement cooling rings  114  with respect to the radial portion  118  of the heat shield panel  82  may provide more uniform cooling of the heat shield  82 , more uniform cross flow of cooling air within the impingement cooling chamber  104 , as well as more uniform backpressure of the cooling air within the impingement cooling chamber  104 . As a result, impingement cooling of the heat shield panel  82  may be improved while minimizing the accumulation of dirt/debris within the impingement cooling chamber  104 . 
     While various aspects of the present disclosure have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the present disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these particular features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the present disclosure. References to “various embodiments,” “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents.