Patent Publication Number: US-2023143185-A1

Title: Combustion liner

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of Indian Patent Application No. 202111051753, filed on Nov. 11, 2021, which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a combustion liner. In particular, the present disclosure relates to a combustion liner for a combustor in a gas turbine engine, the liner having dilution openings and passages around the dilution openings. 
     BACKGROUND 
     A gas turbine engine includes a combustion section having a combustor that generates combustion gases that are discharged into the turbine section of the engine. The combustion section includes a combustion liner. Current combustion liners include dilution openings in the liner. The dilution openings provide dilution air flow to the combustor. The dilution air flow mixes with primary zone products within the combustor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features and advantages will be apparent from the following description of various exemplary embodiments, as illustrated in the accompanying drawings, wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. 
         FIG.  1    shows a schematic, cross-sectional view of a combustion section of a gas turbine engine, according to an embodiment of the present disclosure. 
         FIG.  2    shows schematic, side perspective view of a dilution passage through a combustion liner for a combustor, according to an embodiment of the present disclosure. 
         FIG.  3    shows a schematic side view of the dilution passage of the liner of  FIG.  2   , according to an embodiment of the present disclosure. 
         FIG.  4    shows a schematic, side perspective view of a mirrored version of the combustion liner of  FIG.  2   , according to an embodiment of the present disclosure. 
         FIG.  5    shows a schematic, side perspective view of the dilution passage of the liner of  FIG.  4   , according to an embodiment of the present disclosure. 
         FIG.  6    shows a schematic, partial, top perspective view of a dilution passage of a liner for a combustor, according to an embodiment of the present disclosure. 
         FIG.  7 A  shows a schematic, partial, bottom perspective view of the dilution passage of the liner of  FIG.  6   , according to an embodiment of the present disclosure. 
         FIG.  7 B  shows a schematic, partial, bottom perspective view of the dilution passage of the liner of  FIG.  6   , according to an embodiment of the present disclosure. 
         FIG.  8    shows a schematic, partial, top perspective view of a dilution passage of a liner for a combustor, according to an embodiment of the present disclosure. 
         FIG.  9    shows a schematic side cross-sectional view of a dilution passage of a combustion liner, according to an embodiment of the present disclosure. 
         FIG.  10    shows a schematic side cross-sectional view of a dilution passage of a combustion liner, according to an embodiment of the present disclosure. 
         FIG.  11    shows a schematic side cross-sectional view of a dilution passage of a combustion liner, according to an embodiment of the present disclosure. 
         FIG.  12    shows a schematic side cross-sectional view of a dilution passage of a combustion liner, according to an embodiment of the present disclosure. 
         FIG.  13    shows a schematic side cross-sectional view of the dilution passages through an outer liner and an inner liner of a combustor, according to an embodiment of the present disclosure. 
         FIG.  14    shows a schematic side cross-sectional view of the dilution passage of the liner of  FIG.  2   , according to an embodiment of the present disclosure. 
         FIG.  15    shows a schematic top view of the dilution passages of an exemplary inner liner and outer liner of a combustor, according to an embodiment of the present disclosure. 
         FIG.  16    shows schematic top view of the dilution passages of an exemplary inner liner and outer liner of a combustor, according to an embodiment of the present disclosure. 
         FIG.  17    shows a schematic flow diagram of a method of causing a dilution flow through a combustor liner of a combustor, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Features, advantages, and embodiments of the present disclosure are set forth or apparent from a consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed. 
     Various embodiments are discussed in detail below. While specific embodiments are discussed, this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure. 
     Reference will now be made in detail to present embodiments of the disclosed subject matter, 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 disclosed subject matter. As used herein, the terms “first,” “second,” “third”, “fourth,” and “exemplary” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “upstream” or “forward” and “downstream” or “aft” 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. For example, “forward” refers to a front end or direction of the engine and “aft” refers to a rear end or direction of the engine. 
     Gas turbine engines, such as those used to power aircrafts or industrial applications, include a compressor, a combustor, and a turbine, disposed about a central engine axis, with the compressor disposed axially upstream of the combustor and the turbine disposed axially downstream of the combustor. The compressor pressurizes a supply of air, the combustor burns a hydrocarbon fuel in the presence of the pressurized air, and the turbine extracts energy from the resultant combustion gases. Air pressure ratio and/or exit temperature of a combustor can be changed to improve gas turbine engine-cycle efficiencies. Further, any change in the air pressure ratio and/or exit temperature of a combustor can impact the operability and the life of the turbine. Combustor exit temperatures above 1100° C. are now common in gas turbine engines while acceptable metal temperatures for the stationary nozzles and rotating blades of a turbine are still limited to 900° C. or 1000° C. Further, the temperature of a turbine blade impacts the mechanical strength of the blade (e.g., creep and fatigue) as well as the oxidation and corrosion resistance of the blade. Maintaining the combustor temperature within an acceptable range can improve the life of the turbine blades and the turbine nozzles considerably. Structurally, combustor liners are provided inside combustors to withstand the extreme thermal loads and extensive combustor liner cooling arrangements are likely to reduce thermal stress in several mechanical parts and components of a gas turbine engine. 
     In a combustor of a gas turbine engine, air generally flows through an outer passage and an inner passage surrounding a combustor liner. The air flows from an upstream end of the combustor liner to a downstream end of the combustor liner. Some of the air flowing through the outer passage and the inner passage is diverted through a number of dilution holes provided in the combustor liner and into a core primary combustion zone as dilution air. One purpose of the dilution air flow is to cool (i.e., quench) the combustion gases within the core primary combustion zone before the gases enter a turbine section. Quenching of the products of combustion from a core primary combustion zone of a combustor must, however, be done quickly and efficiently so that regions of high temperature are minimized, and, thereby, NO x  emissions from the combustion system are reduced. 
     Utilizing discrete dilution holes (also referred to as “discrete holes”) and discrete dilution slots (also referred to as “discrete slots”) through a liner that essentially form flow passages through the liner is known. In a discrete dilution situation, high turbulence is introduced into the core primary combustion zone of a combustor from a number of discrete jets. As a result, good mixing of the combustion products is achieved after dilution. There remains, however, pockets of high temperature regions within the combustor core due to low jet penetration. Further, wake regions formed behind discrete dilution jets and between discrete dilution jets give rise to low cooling and low mixing of the dilution air with the primary combustion products. In annular dilution, on the other hand, jet penetration level is high, but turbulence generated is low resulting in low level mixing of the dilution air with primary zone products post dilution flow entry giving rise to potential higher temperature in the core of the combustor post dilution thereby creating a higher exit temperature profile/pattern and can have a negative impact on combustion efficiency. 
     The present disclosure provides a way to synergistically combine the advantages of discrete dilution and annular dilution. A combustor includes a liner body having a cold side and a hot side. The liner body includes a dilution passage having a concatenated geometry extending through the liner body. A first dilution air flow and a second dilution air flow pass through the dilution passage from the cold side of the combustion liner to the hot side of the combustor liner. The dilution passage integrates the first dilution air flow and the second dilution air flow within the concatenated geometry into an integrated dilution air flow and injects the integrated dilution air flow into a core primary combustion zone of a combustor to attain a predetermined combustion state of the combustor. 
       FIG.  1    shows a schematic, cross-sectional view of a combustion section  100  of a gas turbine engine, according to an embodiment of the present disclosure. The combustion section  100  includes a combustor  112  that generates combustion gases that are discharged into the turbine section (not shown) of the engine. The combustor  112  includes a core primary combustion zone  114 . The core primary combustion zone  114  is bound by an outer liner  116 , an inner liner  118 , and a cowl  120 . Additionally, a diffuser  122  is positioned upstream of the core primary combustion zone  114 . The diffuser  122  receives an airflow from the compressor section (not shown) of the engine and provides the flow of compressed air to the combustor  112 . The diffuser  122  provides the flow of compressed air to cowl  120  of a swirler  124 . Air flows through an outer passage  126  and an inner passage  128 . 
       FIGS.  2  and  3    are schematic representations of a liner for a combustor, according to an embodiment of the present disclosure. Referring to  FIG.  2   , a side perspective view  210  schematically represents a dilution passage  211  extending through a combustion liner for a combustor. Referring to  FIG.  3   , reference numeral  220  indicates a bottom view that shows the dilution passage  211  of  FIG.  2   . The dilution passage  211  has a geometry that is formed by concatenating (or physically joining two adjacent entities end to end, blending them into one entity) an exemplary first geometry and an exemplary second geometry. Referring to  FIGS.  2  and  3   , the first geometry, embodied as a number of discrete holes  212 , and the second geometry, embodied as an annular slot  214  extending through the combustor liner, are concatenated into the dilution passage  211 . 
     The discrete holes  212  and the annular slot  214  are concatenated at a predetermined relative position. Referring to  FIGS.  2  and  3   , the discrete holes  212  are positioned forward or upstream and the annular slot  214  positioned aft or downstream The discrete holes  212  have a semi-circular cross section. Although not shown, a bridge structure may connect the discrete holes  212  to the annular slot  214  to allow for control of a dilution gap between the annular slot  214  and the discrete holes  212 . The bridge structure may be connected to the aft face of the liner forming the annular slot  214  (e.g., aft face  459  of  FIG.  114   ). In some examples, the bridge structure may be welded to the annular slot  214 . The bridge structure may support and control the dilution gap. 
     A first dilution air flow  213 , passing through the discrete holes  212 , is integrated with a second dilution air flow  215  passing through the annular slot  214  into an integrated dilution air flow  217 , within the concatenated geometry of the dilution passage  211 . Further, the integrated dilution air flow  217  is injected into the core primary combustion zone  114  of the combustor  112  of  FIG.  1    to attain a predetermined combustion state of the combustor  112 . 
     The integrated dilution air flow  217  improves a number of desired combustion states of the combustor. The second dilution air flow  215  provides a hydraulic support for the first dilution air flow  213 , improving jet penetration in the process. The integrated dilution air flow  217  reduces temperature in the core primary combustion zone  114  of the combustor  112  of  FIG.  1    and an emission level of nitrogen oxides (NO x ) is rendered compliant with regulatory guidelines. Further, an air split ratio or a distribution or share of the first dilution air flow  213  and the second dilution air flow  215  in the integrated dilution air flow  217  is adjusted to reduce the temperature in the core primary combustion zone  114 . Furthermore, the portion of the second dilution air flow  215  of the integrated dilution air remains closer to the liner around the circumference of the liner and maintains lower liner temperature behind the integrated dilution structure. 
     The integrated dilution air flow  217  aids in rapid quenching and a quick mixing of the first dilution air flow  213  and the second dilution air flow  215  with a number of combustion products in the core primary combustion zone  114  of the combustor  112 . The increased mixing leads to a uniform temperature distribution within the core primary combustion zone  114  of the combustor  112 , and, further, to a combustor liner temperature that conforms with a reference combustor liner temperature. 
       FIG.  4    shows a schematic representation of a mirrored version of the dilution passage  211  of  FIG.  2   , according to an embodiment of the present disclosure. Referring to  FIG.  4   , reference numeral  230  indicates a top perspective view that shows a schematic representation of a dilution passage  231  through a combustion liner of a combustor. The dilution passage  231  concatenates a series of discrete holes  232  with an annular slot  234 , forward (upstream) from the discrete holes  232 . A first dilution air flow  233  passing through discrete holes  232  is integrated with a second dilution air flow  235  passing through the annular slot  234  into an integrated dilution air flow  237 , within the concatenated geometry of the dilution passage  231 . Further, the integrated dilution air flow is injected into the core primary combustion zone  114  of the combustor  112  of  FIG.  1    to attain a predetermined combustion state of the combustor  112 . 
     Referring to  FIG.  5   , reference numeral  240  indicates a side perspective view of the dilution passage  231  of  FIG.  4   . The first dilution air flow  233  passes through discrete holes  232  and the second dilution air flow  235  passes through the annular slot  234 . The second dilution air flow  235  provides a hydraulic shielding for the first dilution air flow  233 , improving jet penetration in the process. 
     Referring to  FIGS.  1  to  5   , a velocity distribution of combustion products within the core primary combustion zone  114  ( FIG.  1   ) of the combustor  112  ( FIG.  1   ) is improved by integrating the first dilution air flow ( 213 ,  233 ) and the second dilution air flow ( 215 ,  235 ) into the integrated dilution air flow ( 217 ,  237 ), within the dilution passage ( 211 ,  231 ). Specifically, low velocity of combustion products, generally associated with a dilution configuration having only discrete dilution holes, is enhanced by the integration of the first dilution air flow and the second dilution air flow into the integrated dilution air flow within the dilution passage. Further, high penetration of dilution air, generally associated with a dilution configuration having only annular dilution passages, is further enhanced by the integration of the first dilution air flow and the second dilution air flow into the integrated dilution air flow within the dilution passage. 
     Further, a temperature distribution of combustion products within the core primary combustion zone  114  ( FIG.  1   ) of the combustor  112  ( FIG.  1   ) is improved by integrating the first dilution air flow ( 213 ,  233 ) and the second dilution air flow ( 215 ,  235 ) into the integrated dilution air flow ( 217 ,  237 ), within the dilution passage ( 211 ,  231 ). Specifically, localization of high temperature near an outer periphery of the core primary combustion zone  114  ( FIG.  1   ), generally associated with a dilution configuration having only discrete dilution holes, is reduced by the integration of the first dilution air flow and the second dilution air flow into the integrated dilution air flow within the dilution passage. Further, localization of high temperature near a central portion of the core primary combustion zone  114  ( FIG.  1   ), generally associated with a dilution configuration having only annular dilution passages, is reduced by the integration of the first dilution air flow and the second dilution air flow into the integrated dilution air flow within the dilution passage. 
     Further, the NO x  emission status within a core primary combustion zone  114  ( FIG.  1   ) in the combustor  112  ( FIG.  1   ) is improved by integrating the first dilution air flow ( 213 ,  233 ) and the second dilution air flow ( 215 ,  235 ) into the integrated dilution air flow ( 217 ,  237 ), within the dilution passage ( 211 ,  231 ). Specifically, high NO x  emission near an outer periphery of the core primary combustion zone  114  ( FIG.  1   ), generally associated with a dilution configuration having only discrete dilution holes, is reduced by the integration of the first dilution air flow and the second dilution air flow into the integrated dilution air flow within the dilution passage. Further, high NO x  emission near a central portion of the core primary combustion zone  114  of  FIG.  1   , generally associated with a dilution configuration having only annular dilution passages, is reduced by the integration of the first dilution air flow and the second dilution air flow into the integrated dilution air flow within the dilution passage. 
       FIG.  6    shows a schematic, partial top perspective view of a liner  310 . The liner  310  may include a dilution array  318 . The dilution array  318  includes a plurality of dilution passages  311 . The dilution array  318  concatenates the plurality of dilution passages  311  together. As shown in  FIG.  6   , the plurality of dilution passages  311  may be arranged in a linear array. Although a single linear arrangement of the plurality of dilution passages  311  is shown, the linear array may be repeated along the axial length of the liner  310 . 
     Each dilution passage  311  includes a discrete, shaped hole  312 , also referred to as a discrete hole  312 , with a corresponding slot, embodied as a discrete slot  314 . The discrete slot  314  has a slot width  372 . Each of the discrete slots  314  may be an elongated slot adjacent to and abutting a respective discrete, shaped hole  312 . The discrete slot  314  extends on either side of a perimeter or boundary of the discrete hole  312  and the length of extension on either side, referred to as a slot extension  374 , is within a range of 0.5 times to fifteen times the slot width  372 . The slot extension  374  may include a first slot extension  374  extending circumferentially in a first direction from a first side of the discrete hole  312  and a second slot extension  374  extending circumferentially in a second direction from a second side of the discrete hole  312 . The first direction may oppose the second direction. In this manner, the first slot extension  374  and the second slot extension  374  may extend circumferentially away from each other and away from the discrete hole  312 . 
     A first dilution air flow  313  passing through the discrete holes  312  is integrated with a second dilution air flow  315  passing through the discrete slot  314  to form an integrated dilution air flow  317 , comprising both the first dilution air flow  313  and the second dilution air flow  315 . The integrated dilution air flow  317  is injected into the core primary combustion zone  114  ( FIG.  1   ) of the combustor  112  ( FIG.  1   ) to attain a predetermined combustion state of the combustor  112  ( FIG.  1   ). 
     With continued reference to  FIG.  6   , the discrete slots  314  may be discrete, forward positioned discrete slots. The discrete, shaped holes  312  may be discrete aft positioned, shaped holes or plain holes. Although shown and described with the discrete, shaped holes  312  located aft of the discrete slots  314  (e.g., the discrete, shaped holes  312  downstream of the discrete slots  314 ), the reverse is also considered such that the discrete, shaped holes  312  are located forward of the discrete slots  314  on the liner  310  (e.g., the discrete, shaped holes  312  upstream of the discrete slots  314 ). 
     The relative location of the discrete, shaped holes  312  and discrete slots  314  may, together, improve a turbulence level in the core primary combustion zone  114  ( FIG.  1   ) within the combustor  112  ( FIG.  1   ). For example, the discrete slot  314  positioned in front of (e.g., forward of or upstream of) the discrete hole  312 , also referred to as a discrete dilution hole  312 , and extending beyond the discrete holes  312  (e.g., the slot extension  374 ) provides hydraulic shielding and improves penetration of the dilution air flow into the core primary combustion zone  114  ( FIG.  1   ). Portions of the second dilution air flow  315  from the discrete slot  314  get drawn behind discrete jets that are a portion of the first dilution air flow  313  from the discrete holes  312 . This may reduce the temperature behind the jets to reduce NO x  emission. Portions of the second dilution air flow  315  from the discrete slot  314  that extend beyond the discrete holes  312  may reduce the temperature between adjacent discrete jets of the first dilution air flow  313  from the discrete holes  312  (e.g., discrete holes  312  located next to each other on the liner  310  with no intervening discrete holes  312 ). 
       FIG.  7 A  shows a partial, bottom perspective view of the dilution array  318  of the liner  310  having of  FIG.  6   . The liner  310  has a liner body  309  having a hot side  353  and a cold side  357 . Each of the plurality of dilution passages  311  includes protruding dilution inserts  316 . The dilution inserts  316  are full-length dilution inserts with a same weighted area extending from a forward side of the dilution insert  316  to an aft side of the dilution insert  316 . That is, the dilution inserts  316  have a uniform height  376  (e.g., a height of the dilution insert  316  on the hot side of the liner  310 ) from the forward side to the aft side. In some examples, the height  376  of the dilution insert  316  may be tapered, for example, may be zero at the forward side and the length can progressively increase to a full length at the aft side of the dilution insert. In some examples, the height  376  of the dilution insert  316  may be within 0.1 times to ten times a diameter D ( FIG.  6   ) of the discrete holes  312  ( FIG.  6   ). As shown in  FIG.  7 A , the first dilution air flow  313  and the second dilution air flow  315  may combine to form the integrated dilution air flow  317 . 
     In the example of  FIG.  7 B , the dilution insert  316  extending from the liner body  309  may include a slant cut  329  on the hot side of the dilution insert  316  such that the height varies from the forward side toward the aft side. The slant cut  329  may be made at an angle theta  378 . Angle theta  378  is defined to be the angle between a discrete dilution center axis  346  and an angled cutting plane  348 . The angle cutting plane  348  may be aligned with the slant cut  329 . The value of the angle theta  378  can vary from zero degree to eighty degrees. 
     In the example of  FIG.  8   , the dilution array  318  may include the plurality of dilution passages  311  arranged in a staggered array. In this manner, the dilution array  318  may include a first row  319  and a second row  320 . The first row  319  may be axially offset rom the second row  320 . For example, a first centerline  352  of a dilution passage  311  in the first row  319  and a second centerline  354  of a dilution passage  311  in the second row  320  may be an axial offset  382 . A length of the axial offset  382  may be within a range of zero to (+/−) five times the diameter of the discrete hole  312 . The integrated dilution holes on outer and inner liners are either opposed or staggered circumferentially relative to each other. Although a single dilution array  318  having the first row  319  and the second row  320  is shown, the array may be repeated along the axial length of the liner  310  such that a plurality of first rows  319  and second rows  320  are present. 
     Any of the examples of  FIGS.  6  to  8    may be combined with any or all of the examples of  FIGS.  6  to  8   . 
       FIG.  9    shows a schematic side cross-sectional view of a dilution passage  411  of a combustion liner  442 . The combustion liner  442  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  9   , a side view  440  schematically represents the dilution passage  411 , which may be similar to the dilution passage  411  of  FIG.  2   . The dilution passage  411  extends through the combustion liner  442  of a combustor. The combustion liner  442  may be an inner liner or an outer liner of the combustion chamber. The dilution passage  411  has a geometry that is formed by concatenating a series of discrete dilution holes  444  and a discrete dilution slot  454 . Each discrete dilution hole  444  may be semicircular in cross section. For example, in a top view of the discrete dilution holes  444 , a geometry  450  of the discrete dilution holes  444  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  446  of each of the discrete dilution holes  444 . That is, an axis extending through the center of the diameter of the discrete dilution holes  444  aligns with the centerline  446 . The discrete dilution slot  454  may have a forward face  458  and an aft face  459 . 
     With continued reference to  FIG.  9   , the centerlines  446  of the discrete dilution holes  444  are parallel to a centerline  456  of the discrete dilution slot  454 . The forward face  458  of the discrete dilution slot  454  merges and aligns with each of the diameters of the discrete dilution holes  444 , which may have a semicircular geometry. Thus, the centerlines  446  of the discrete dilution holes  444  are in line with the forward face  458  of the discrete dilution slot  454  at the axial location of the forward face  458  of the discrete dilution slot  454 , such as shown in the top view. Further, ten percent to ninety percent of a total flow area of the dilution passage  411  is occupied by the discrete dilution holes  444  and the rest of the total flow area is occupied by the discrete dilution slot  454 . 
       FIG.  10    shows a schematic side view cross-sectional of a dilution passage  431  of a combustion liner  462 . The combustion liner  462  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  10   , a side view  460  schematically represents the dilution passage  431 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  431  extends through the combustion liner  462  of a combustor. The dilution passage  411  has a geometry that is formed by concatenating a series of discrete dilution holes  464  and a discrete dilution slot  474 . Each discrete dilution hole  464  may be semicircular in cross section. For example, in a top view of the discrete dilution holes  464 , a geometry  470  of the discrete dilution holes  464  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  466  of each of the discrete dilution holes  464 . That is, an axis extending through the center of the diameter of the discrete dilution hole  464  aligns with the centerline  466 . The discrete dilution slot  474  may have a forward face  478  and an aft face  479 . 
     With continued reference to  FIG.  10   , the centerlines  466  of the discrete dilution holes  464  are parallel to a centerline  476  of the discrete dilution slot  474 . Further, the centerlines  466  of the discrete dilution holes  464  are in line with the aft face  479  of the discrete dilution slot  474  at the axial location of the aft face  479  of the discrete dilution slot  474 . 
       FIG.  11    shows a schematic side cross-sectional view of a dilution passage  511  of a combustion liner  522 . The combustion liner  522  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  11   , a side view  520  schematically represents the dilution passage  511 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  511  extends through the combustion liner  522  of a combustor. The dilution passage  511  has a geometry that is formed by concatenating a series of discrete dilution holes  524  and a discrete dilution slot  534 . Each discrete dilution hole  524  may be semicircular in cross section. For example, in a top view of the discrete dilution hole  524 , a geometry  530  of the discrete dilution hole  524  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  526  of each of the discrete dilution hole  524 . That is, an axis extending through the center of the diameter of the discrete dilution hole  524  aligns with the centerline  526 . The discrete dilution slot  534  may have a forward face  538  and an aft face  539 . 
     With continued reference to  FIG.  11   , the centerlines  526  of the discrete dilution holes  524  are parallel to a centerline  536  of the discrete dilution slot  534 . Further, the centerlines  526  of the discrete dilution holes  524  are aft of the aft face  539  of the discrete dilution slot  534  at the axial location of the aft face  539  of the discrete dilution slot  534 . An offset  532 , measured between the centerlines  526  of the discrete dilution holes  524  and the forward face  538  of the discrete dilution slot  534  is between zero to 0.3 times the diameter D of the discrete dilution holes  524 . 
       FIG.  12    shows a schematic side cross-sectional view of a dilution passage  531  of a combustion liner  542 . The combustion liner  542  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  12   , a side view  540  schematically represents the dilution passage  531 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  531  extends through the combustion liner  542  of a combustor. The dilution passage  531  has a geometry that is formed by concatenating a series of discrete dilution holes  544  and a discrete dilution slot  554 . Each discrete dilution hole  544  may be semicircular in cross section. For example, in a top view of the discrete dilution hole  544 , a geometry  550  of the discrete dilution hole  544  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  546  of each of the discrete dilution holes  524 . That is, an axis extending through the center of the diameter of the discrete dilution hole  544  aligns with the centerline  546 . The discrete dilution slot  554  may have a forward face  558  and an aft face  559 . 
     With continued reference to  FIG.  12   , the centerlines  546  of the discrete dilution holes  544  are parallel to a centerline  556  of the discrete dilution slot  554 . Further, the centerlines  546  of the discrete dilution holes  544  are forward of the forward face  558  of the discrete dilution slot  534  at the axial location of the forward face  558  of the discrete dilution slot  554 . An offset  552 , measured between the centerlines  546  of the discrete dilution holes  544  and the forward face  558  of the discrete dilution slot  534  is between zero to one time the diameter D of the discrete dilution holes  544 . 
       FIG.  13    shows a schematic side cross-sectional view  560  of a first dilution passage  551  through an outer liner  562  and a second dilution passage  561  through an inner liner  582  of a combustor, according to an embodiment of the present disclosure. The first dilution passage  551  has a geometry that is formed by concatenating a series of discrete dilution holes  564  and a discrete dilution slot  574 . Centerlines  566  of the discrete dilution holes  564  are parallel with a centerline  576  of the discrete dilution slot  574  and in line with a forward face  578  of the discrete dilution slot  574  at the axial location of the forward face  578  of the discrete dilution slot  574 . The second dilution passage  561  has a geometry that is formed by concatenating a series of discrete dilution holes  584  and a discrete dilution slot  594 . Centerlines  586  of the discrete dilution holes  584  are parallel with a centerline  596  of the discrete dilution slot  594  and in line with a forward face  598  of the discrete dilution slot  594  at the axial location of the forward face  598  of the discrete dilution slot  594 . An offset  580 , measured between the centerlines  566  of the discrete dilution holes  564  on the outer liner  562  and the centerlines  586  of the discrete dilution holes  584  on the inner liner  582 , is between zero to +/− six times a diameter of the discrete dilution holes  564  or  584 . 
       FIG.  14    shows a schematic side cross-sectional view  620  of a dilution passage  611  of a combustion liner  622 . The dilution passage  611  has a geometry that is formed by concatenating a series of discrete dilution holes  624  and a discrete dilution slot  634 . Centerlines  626  of the discrete dilution holes  624  are parallel to a centerline  636  of the discrete dilution slot  634 . The centerlines  626  of the discrete dilution holes  624  and/or the centerline  636  of the discrete dilution slot  634 , that is, the flow direction of the discrete hole and discrete slot flows, may be inclined at an angle theta  632 , defined with respect to an axis  630  normal to the combustion liner  622 . The angle theta may be from minus sixty degrees (inclined forward) to positive sixty degrees (inclined aft). Centerlines  626  of the discrete dilution holes  624  may be normal to the combustion liner  622  and centerline  636  of the discrete dilution slot  634  inclined at the theta angle and vice versa. Although shown as being aligned with the centerline  636 , the centerlines  626  may be offset in any of the previously described manners with respect to the description of  FIGS.  9  to  13   . 
       FIGS.  15  and  16    each shows a schematic top view of the dilution passages of exemplary inner liner and outer liner of a combustor, such as combustor  112  ( FIG.  1   ), according to an embodiment of the present disclosure. A schematic outline of the dilution holes of an outer liner are shown overlain on the dilution holes of an inner liner. That is, when viewing the liner from a top view, the outline of the dilution holes of the inner liner and outer liner may appear as shown in either of  FIG.  15  or  16   . 
     For example,  FIG.  15    shows a top view  640  of an outer liner  642  and an inner liner  652 . The outer liner  642  has a series of outer liner discrete dilution holes including an outer liner discrete dilution hole  644  and an outer liner discrete dilution hole  646 . Although two outer liner discrete dilution holes are shown, more may be provided. The inner liner  652  has a series of inner liner discrete dilution holes including an inner liner discrete dilution hole  654  and an inner liner discrete dilution hole  656 . Although two inner liner discrete dilution holes are show, more may be provided. 
     The outer liner discrete dilution hole  644  and the outer liner discrete dilution hole  646  may directly oppose or may be angularly staggered with the inner liner discrete dilution hole  654  and the inner liner discrete dilution hole  656 . In this manner, when the series of outer liner discrete dilution holes and inner liner discrete dilution holes are axially aligned, the inner liner discrete dilution hole  654  is circumferentially between the outer liner discrete dilution hole  644  and the outer liner discrete dilution hole  646 . The inner liner discrete dilution hole  656  may be located between the outer liner discrete dilution hole  646  and a not shown, adjacent outer liner discrete dilution hole. Each of the inner liner discrete dilution holes may be halfway between adjacent outer liner discrete dilution holes. 
     Although shown and described as being staggered halfway, other offsets between the outer liner discrete dilution holes  644  and  646  and the inner liner discrete dilution holes  654  and  656  are contemplated. For example,  FIG.  16   , a top view  660  of an outer liner  662  and an inner liner  672 . The outer liner  662  has a series of outer liner discrete dilution holes including an outer liner discrete dilution hole  664  and an outer liner discrete dilution hole  666 . Although two outer liner discrete dilution holes are shown, more may be provided. The inner liner  672  has a series of inner liner discrete dilution holes including an inner liner discrete dilution hole  674  and an inner liner discrete dilution hole  676 . Although two inner liner discrete dilution holes are show, more may be provided. The top liners of  FIG.  16    may be the same as the liners of  FIG.  15   , however, the inner liner discrete dilution hole  674  and the inner liner discrete dilution hole  676  may be positioned circumferentially closer to the outer liner discrete dilution hole  664  and the outer liner discrete dilution hole  666 , respectively, as compared to  FIG.  15   . That is, a distance between an inner liner discrete dilution hole, such as inner liner discrete dilution hole  674  and a first outer liner discrete dilution hole, such as the outer liner discrete dilution hole  664 , may be smaller than a distance between the same inner liner discrete dilution hole (e.g., inner liner discrete dilution hole  674 ) and an outer liner discrete dilution hole adjacent to the first outer liner discrete dilution hole (e.g., outer liner discrete dilution hole  666 ). This relationship may be reversed and any distance between the dilution holes may be provided. 
     There may be other positional locations of the inner liner discrete dilution holes with respect to the outer liner discrete dilution holes in addition to, or as alternatives to, the two positions mentioned above. Further, outer liner discrete holes may be in line with a center of a swirler or at an angle with respect to the swirler. The angle may depend on the number of discrete holes per swirler cup liner. 
       FIG.  17    shows a schematic flow diagram of a method  700  of causing a dilution flow through a combustor liner, according to an embodiment of the present disclosure. The method  700  includes providing a combustor having (i) a combustor liner body with a hot side and a cold side, and (ii) a core primary combustion zone of the combustor, as shown in step  712 . The method  700  also includes extending a dilution passage having a concatenated geometry through the combustor liner body, as shown in step  714 . The method  700  further includes causing a first dilution air to flow through the dilution passage from the cold side to the hot side of the combustor liner, as shown in step  716 . The method also includes causing a second dilution air to flow through the dilution passage from the cold side to the hot side of the combustor liner, as shown in step  718 . 
     The concatenated geometry of the dilution passage is formed by concatenating a first geometry and a second geometry at a predetermined relative position such that the first dilution air and the second dilution air are integrated within the combined geometry of the dilution passage. The first geometry can be positioned forward or upstream with the second geometry positioned aft or downstream. The second geometry can be positioned forward or upstream with the first geometry positioned aft or downstream. 
     The first geometry includes at least one discrete hole and the second geometry includes at least one discrete dilution slot. The size of the discrete features such as the holes and the discrete slots, discretely positioned, can be varied circumferentially or can have a particular pattern along the circumference. The discrete holes can have a semi-circular cross section, or a triangular cross section, or a semi-elliptical cross section with a major axis in a lateral direction, or a semi-elliptical cross section with a major axis in an axial direction, or any combination thereof. 
     The concatenated geometry of the dilution passage can repeat in a predetermined pattern such as in a linear array substantially circumferential with respect to the combustor, or in a staggered array. The dilution passages can be oriented in a varying angle of predetermined orientation in relation to the combustor. The dilution passages can be arranged normal to an axis of the liner, or the dilution passages can be inclined at an angle to the axis of the swirler. 
     The method  700  further includes providing a third geometry and concatenating the third geometry with the first geometry such that the first dilution air flows through the third geometry. The third geometry is a protruding dilution insert extending into the hot side of the liner. The protruding dilution insert can be a full-length insert, or an angled-cut (or slant cut) dilution insert, or a fence. The length of the protruding dilution inserts can be more on one side than on another such that weighted areas reduce from one side to other. The exact dimensions of the protruding dilution inserts can be adjusted for effective performance. 
     The method  700  further includes integrating the first dilution air flow and the second dilution air flow to provide an integrated dilution air flow to increase mixing with a number of combustion products in a primary combustion zone of the combustor, as shown in step  722 . The method  700  also includes injecting the integrated dilution air flow into the combustor to attain a predetermined combustion state of the combustor, as shown in step  724 . 
     The predetermined combustion state of the combustor includes a compliant NO x  emission level. The predetermined combustion state of the combustor further includes reducing a temperature in a core primary combustion zone of the combustor. The predetermined combustion state of the combustor further includes a reduced temperature in a core primary combustion zone of the combustor. The predetermined combustion state of the combustor further includes reducing a temperature in a wake region of the dilution jet or dilution insert. The predetermined combustion state of the combustor further includes reducing a temperature between dilution jets or a dilution insert. The predetermined combustion state of the combustor also includes a uniform temperature distribution within a primary and secondary combustion zone of the combustor. The predetermined combustion state of the combustor includes a combustor exit temperature profile conforming with a reference temperature profile. The predetermined combustion state of the combustor also includes rapid quenching and a quick and an increased mixing of the first dilution air flow and the second dilution air flow with combustion products in a primary combustion zone of the combustor. Further, the predetermined combustion state of the combustor includes a balance of a predetermined air split ratio (relative distribution or share) of the first dilution air flow and the second dilution air flow. 
     The liner for a gas turbine engine combustor of the present disclosure provides a dilution passage with a concatenated geometry that integrates a first dilution air flow and a second dilution air flow into an integrated dilution air flow. 
     When the second dilution air flow is downstream of the first dilution air flow, the second dilution air flow may provide a hydraulic support to the first dilution air flow. When the second dilution air flow is upstream of the first dilution air flow, the second dilution air flow may provide a hydraulic shield for the first dilution air flow. In both cases, the hydraulic support and/or hydraulic shielding may percolate between the discrete jets of the first dilution air flow and enhance a penetration of the first dilution air flow into a core primary combustion zone of the combustor. 
     The integrated dilution air flow increases rapid quenching and mixing of the dilution air flows with a number of combustion products in a primary combustion zone of the combustor leading to a uniform temperature distribution within the primary combustion zone of the combustor and a combustor exit temperature profile conforming with a reference temperature profile. The integrated dilution air flow reduces an emission level of nitrogen oxides (NO x ) in a core primary combustion zone of the combustor in compliance with regulatory guidelines. 
     Further aspects of the present disclosure are provided by the subject matter of the following clauses. 
     A liner for a combustor in a gas turbine engine. The liner body has a liner body having a cold side and a hot side, and a dilution array having a plurality of dilution passages. Each dilution passage of the plurality of dilution passages comprising a concatenated geometry repeating in a predetermined pattern and extending circumferentially around the liner body. The dilution passage is configured (i) to integrate a first dilution air flow flowing through the dilution passage from the cold side to the hot side and a second dilution air flow flowing through the dilution passage from the cold side to the hot side into an integrated dilution air flow, and (ii) to inject the integrated dilution air flow into a core primary combustion zone of the combustor to attain a predetermined combustion state of the combustor. The dilution array is repeated along an axial length of the liner body. 
     The liner of the preceding clause, wherein the second dilution air flow fills a region of wakes formed behind a plurality of discrete jets of the first dilution air flow. 
     The liner of any preceding clause, wherein the first dilution air flow is ten percent to ninety percent of a total flow through the plurality of dilution passages. 
     The liner of any preceding clause, wherein the first dilution air flow is located axially aft of the second dilution air flow. 
     The liner of any preceding clause, wherein the first dilution air flow is located axially forward of the second dilution air flow. 
     The liner of any preceding clause, wherein each of the plurality of dilution passages comprises a discrete slot and a discrete hole. 
     The liner of any preceding clause, wherein the discrete slot has a first slot extension extending circumferentially in a first direction from a first side of the discrete hole and a second slot extension extending circumferentially in a second direction from a second side of the discrete hole, wherein the first direction opposes the second direction. 
     The liner of any preceding clause, wherein the first slot extension and the second slot extension are each within a range of 0.5 times to fifteen times a slot width of the discrete slot. 
     The liner of any preceding clause, wherein each of the plurality of dilution passages comprises a dilution insert extending radially inward toward a centerline of the combustor from the hot side of the liner body. 
     The liner of any preceding clause, wherein the dilution insert has a constant height from a forward side of the dilution insert to an aft side of the dilution insert. 
     The liner of any preceding clause, wherein the dilution insert has a variable height from a forward side of the dilution insert to an aft side of the dilution insert. 
     The liner of any preceding clause, wherein each of the plurality of dilution passages further comprises a discrete slot and a discrete hole, and the dilution insert has a height within a range of 0.1 times to ten times a diameter of the discrete hole. 
     The liner of any preceding clause, wherein the dilution insert has a slant cut along a forward side of the dilution insert. 
     The liner of any preceding clause, wherein the concatenated geometry comprises at least a first geometry and a second geometry concatenated at a predetermined relative position and wherein the first dilution air flow flows through the first geometry and the second dilution air flow flows through the second geometry. 
     The liner of any preceding clause, wherein the first geometry comprises a discrete hole having a semi-circular cross section. 
     The liner of any preceding clause, wherein the first geometry comprises at least one discrete hole and the second geometry comprises at least one discrete slot. 
     The liner of any preceding clause, wherein the predetermined pattern is a linear array. 
     The liner of any preceding clause, wherein the linear array comprises the plurality of dilution passages arranged along a common axis around a circumference of the liner body. 
     The liner of any preceding clause, wherein the predetermined pattern comprises a staggered array. The liner of any preceding clause, wherein the staggered array comprises a first row of the plurality of dilution passages and a second row of the plurality of dilution passages, a centerline of the plurality of dilution passages in the first row being axially offset from a centerline of the plurality of dilution passages in the second row. 
     Although the foregoing description is directed to the preferred embodiments, it is noted that other variations and modifications will be apparent to those skilled in the art, and may be made without departing from the spirit or scope of the disclosure Moreover, features described in connection with one embodiment may be used in conjunction with other embodiments, even if not explicitly stated above.