Patent Publication Number: US-2023144971-A1

Title: Combustion liner

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of Indian Patent Application No. 202111051692, 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 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 side cross-sectional view of a dilution passage of a combustion liner, according to an embodiment of the present disclosure. 
         FIG.  7    shows a schematic side cross-sectional view of a dilution passage of a combustion liner, according to an embodiment of the present disclosure. 
         FIG.  8    shows a schematic side cross-sectional view of a dilution passage of a combustion liner, 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 the dilution passages through an outer liner and an inner liner of a combustor, according to an embodiment of the present disclosure. 
         FIG.  11    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.  12    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.  13    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.  14    shows a schematic, side perspective view of the flow dynamics through a liner for a combustor of  FIG.  3   , according to an embodiment of the present disclosure. 
         FIG.  15    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 
     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 annular dilution slots (also referred to as “annular 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 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 by providing 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  359  of  FIG.  6   ). 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 the 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 the 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 side cross-sectional view of a dilution passage  311  of a combustion liner  342 . The combustion liner  342  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  6   , a side view  340  schematically represents the dilution passage  311 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  311  extends through the combustion liner  342  of a combustor. The combustion liner  342  may be an inner liner or an outer liner of the combustion chamber. The dilution passage  311  has a geometry that is formed by concatenating a series of discrete dilution holes  344  and an annular dilution slot  354 . Each discrete dilution hole  344  may be semicircular in cross section. For example, in a top view of the discrete dilution hole  344 , a geometry  350  of the discrete dilution hole  344  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  346  of each of the discrete dilution hole  344 . That is, an axis extending through the center of the diameter of the discrete dilution hole  344  aligns with the centerline  346 . The annular dilution slot  354  may have a forward face  358  and an aft face  359 . 
     With continued reference to  FIG.  6   , the centerlines  346  of the discrete dilution holes  344  are parallel to a centerline  356  of the annular dilution slot  354 . The forward face  358  of the annular dilution slot  354  merges and aligns with each of the diameters of the discrete dilution holes  344 , which may have a semicircular geometry. Thus, the centerlines  346  of the discrete dilution holes  344  are in line with the forward face  358  of the annular dilution slot  354  at the axial location of the forward face  358  of the annular dilution slot  354 , such as shown in the top view. Further, ten percent to ninety percent of a total flow area of the dilution passage  311  is occupied by the discrete dilution holes  344  and the rest of the total flow area is occupied by the annular dilution slot  354 . 
       FIG.  7    shows a schematic side view cross-sectional of a dilution passage  331  of a combustion liner  362 . The combustion liner  362  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  7   , a side view  360  schematically represents the dilution passage  331 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  331  extends through the combustion liner  362  of a combustor. The dilution passage  311  has a geometry that is formed by concatenating a series of discrete dilution holes  364  and an annular dilution slot  374 . Each discrete dilution hole  364  may be semicircular in cross section. For example, in a top view of the discrete dilution hole  364 , a geometry  370  of the discrete dilution hole  364  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  366  of each of the discrete dilution hole  364 . That is, an axis extending through the center of the diameter of the discrete dilution hole  364  aligns with the centerline  366 . The annular dilution slot  374  may have a forward face  378  and an aft face  379 . 
     With continued reference to  FIG.  7   , the centerlines  366  of the discrete dilution holes  364  are parallel to a centerline  376  of the annular dilution slot  374 . Further, the centerlines  366  of the discrete dilution holes  364  are in line with the aft face  379  of the annular dilution slot  374  at the axial location of the aft face  379  of the annular dilution slot  374 . 
       FIG.  8    shows a schematic side cross-sectional view of a dilution passage  411  of a combustion liner  422 . The combustion liner  422  may be the same as or similar to the combustion liner of  FIG.  2   . Referring to  FIG.  8   , a side view  420  schematically represents the dilution passage  411 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  411  extends through the combustion liner  422  of a combustor. The dilution passage  411  has a geometry that is formed by concatenating a series of discrete dilution holes  424  and an annular dilution slot  434 . Each discrete dilution hole  424  may be semicircular in cross section. For example, in a top view of the discrete dilution hole  424 , a geometry  430  of the discrete dilution hole  424  may be semicircular. A centerline of the circle formed by two halves of the semi-circle may be a centerline  426  of each of the discrete dilution hole  424 . That is, an axis extending through the center of the diameter of the discrete dilution hole  424  aligns with the centerline  426 . The annular dilution slot  434  may have a forward face  438  and an aft face  439 . 
     With continued reference to  FIG.  8   , the centerlines  426  of the discrete dilution holes  424  are parallel to a centerline  436  of the annular dilution slot  434 . Further, the centerlines  426  of the discrete dilution holes  424  are aft of the aft face  439  of the annular dilution slot  434  at the axial location of the aft face  439  of the annular dilution slot  434 . An offset  432 , measured between the centerlines  426  of the discrete dilution holes  424  and the forward face  438  of the annular dilution slot  434 , is between zero to 0.3 times the diameter D of the discrete dilution holes  424 . 
       FIG.  9    shows a schematic side cross-sectional view of a dilution passage  431  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  431 , which may be similar to the dilution passage  211  of  FIG.  2   . The dilution passage  431  extends through the combustion liner  442  of a combustor. The dilution passage  431  has a geometry that is formed by concatenating a series of discrete dilution holes  444  and an annular dilution slot  454 . Each discrete dilution hole  444  may be semicircular in cross section. For example, in a top view of the discrete dilution hole  444 , a geometry  450  of the discrete dilution hole  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 hole  424 . That is, an axis extending through the center of the diameter of the discrete dilution hole  444  aligns with the centerline  446 . The annular 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 annular dilution slot  454 . Further, the centerlines  446  of the discrete dilution holes  444  are forward of the forward face  458  of the annular dilution slot  434  at the axial location of the forward face  458  of the annular dilution slot  454 . An offset  452 , measured between the centerlines  446  of the discrete dilution holes  444  and the forward face  458  of the annular dilution slot  434  is between zero to one time the diameter D of the discrete dilution holes  444 . 
       FIG.  10    shows a schematic side cross-sectional view  460  of a first dilution passage  451  through an outer liner  462  and a second dilution passage  461  through an inner liner  482  of a combustor, according to an embodiment of the present disclosure. The first dilution passage  451  has a geometry that is formed by concatenating a series of discrete dilution holes  464  and an annular dilution slot  474 . Centerlines  466  of the discrete dilution holes  464  are parallel with a centerline  476  of the annular dilution slot  474  and in line with a forward face  478  of the annular dilution slot  474  at the axial location of the forward face  478  of the annular dilution slot  474 . The second dilution passage  461  has a geometry that is formed by concatenating a series of discrete dilution holes  484  and an annular dilution slot  494 . Centerlines  486  of the discrete dilution holes  484  are parallel with a centerline  496  of the annular dilution slot  494  and in line with a forward face  498  of the annular dilution slot  494  at the axial location of the forward face  498  of the annular dilution slot  494 . An offset  480 , measured between the centerlines  466  of the discrete dilution holes  464  on the outer liner  462  and the centerlines  486  of the discrete dilution holes  484  on the inner liner  482 , is between zero to +/−six times a diameter of the discrete dilution holes  464  or  484 . 
       FIG.  11    shows a schematic side cross-sectional view  520  of a dilution passage  511  of a combustion liner  522 . The dilution passage  511  has a geometry that is formed by concatenating a series of discrete dilution holes  524  and an annular dilution slot  534 . Centerlines  526  of the discrete dilution holes  524  are parallel to a centerline  536  of the annular dilution slot  534 . The centerlines  526  of the discrete dilution holes  524  and/or the centerline  536  of the annular dilution slot  534 , that is, the flow direction of the discrete and annular flows, may be inclined at an angle theta  532 , defined with respect to an axis  530  normal to the combustion liner  522 . The angle theta may be from minus sixty degrees (inclined forward) to positive sixty degrees (inclined aft). Centerlines  526  of the discrete dilution holes  524  may be normal to the combustion liner  522  and centerline  536  of the annular dilution slot  534  inclined at the theta angle and vice versa. Although shown as being aligned with the centerline  536 , the centerlines  526  may be offset in any of the previously described manners with respect to the description of  FIGS.  7  to  10   . 
       FIGS.  12  and  13    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.  12  or  13   . 
     For example,  FIG.  12    shows a top view  540  of an outer liner  542  and an inner liner  552 . The outer liner  542  has a series of outer liner discrete dilution holes including an outer liner discrete dilution hole  544  and an outer liner discrete dilution hole  546 . Although two outer liner discrete dilution holes are shown, more may be provided. The inner liner  552  has a series of inner liner discrete dilution holes including an inner liner discrete dilution hole  554  and an inner liner discrete dilution hole  556 . Although two inner liner discrete dilution holes are show, more may be provided. 
     The outer liner discrete dilution hole  544  and the outer liner discrete dilution hole  546  may directly oppose or may be angularly staggered with the inner liner discrete dilution hole  554  and the inner liner discrete dilution hole  556 . 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  554  is circumferentially between the outer liner discrete dilution hole  544  and the outer liner discrete dilution hole  546 . The inner liner discrete dilution hole  556  may be located between the outer liner discrete dilution hole  546  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  544  and  546  and the inner liner discrete dilution holes  554  and  556  are contemplated. For example,  FIG.  13   , a top view  560  of an outer liner  562  and an inner liner  572 . The outer liner  562  has a series of outer liner discrete dilution holes including an outer liner discrete dilution hole  564  and an outer liner discrete dilution hole  566 . Although two outer liner discrete dilution holes are shown, more may be provided. The inner liner  572  has a series of inner liner discrete dilution holes including an inner liner discrete dilution hole  574  and an inner liner discrete dilution hole  576 . Although two inner liner discrete dilution holes are show, more may be provided. The top liners of  FIG.  13    may be the same as the liners of  FIG.  12   , however, the inner liner discrete dilution hole  574  and the inner liner discrete dilution hole  576  may be positioned circumferentially closer to the outer liner discrete dilution hole  564  and the outer liner discrete dilution hole  566 , respectively, as compared to  FIG.  13   . That is, a distance between an inner liner discrete dilution hole, such as inner liner discrete dilution hole  574  and a first outer liner discrete dilution hole, such as the outer liner discrete dilution hole  564 , may be smaller than a distance between the same inner liner discrete dilution hole (e.g., inner liner discrete dilution hole  574 ) and an outer liner discrete dilution hole adjacent to the first outer liner discrete dilution hole (e.g., outer liner discrete dilution hole  566 ). 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.  14    shows a schematic, bottom perspective view of flow dynamics through a liner for a combustor of  FIG.  3   , according to an embodiment of the present disclosure.  FIG.  14    is a schematic representation of the flow dynamics associated with the dilution passage  211  of  FIG.  3   . Referring to  FIG.  14   , reference numeral  220  indicates a bottom view that shows the dilution passage  211  of  FIG.  2   , that concatenates the discrete hole  212  with the annular slot  214 . The first dilution air flow  213 , passing through the discrete holes  212 , is integrated with the second dilution air flow  215  passing through the annular slot  214  into the integrated dilution air flow  217 , within the concatenated geometry of the dilution passage  211 . 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 . 
     The first dilution air flow  213  generates a turbulence in the core primary combustion zone  114  of the combustor  112  of  FIG.  1   . The first dilution air flow  213  through the discrete dilution holes may produce a region of wakes behind the first dilution air flow  213  exiting each of the discrete dilution holes. The second dilution air flow  215  fills the region of wakes formed behind a number of discrete jets of the first dilution air flow  213 . Further, the second dilution air flow  215  provides a hydraulic support to the first dilution air flow  213  and enhances a penetration of the first dilution air flow  213  into the core primary combustion zone  114  of the combustor  112 . Further, the second dilution air flow  215  percolates between the discrete jets of the first dilution air flow  213  and prevents development of any high temperature zone in proximity of the liner and in regions between the discrete jets of the first dilution air flow  213 . Although described with respect to  FIGS.  1  to  3   ,  FIG.  15    may also describe flow in the dilution passages of  FIGS.  4  to  14   . 
       FIG.  15    shows a schematic flow diagram of a method  600  of causing a dilution flow through a combustor liner, according to an embodiment of the present disclosure. The method  600  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  612 . The method  600  also includes extending a dilution passage having a concatenated geometry through the combustor liner body, as shown in step  614 . The method  600  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  616 . 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  618 . 
     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 annular slot. The size of the discrete features such as the holes and the annular 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 with one side of the triangle aligned with and parallel to the annular slot, or a semi-elliptical cross section (e.g., race track) with a major axis in a lateral direction, or a semi-elliptical cross section (e.g., race track) 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  600  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  622 . The method  600  also includes injecting the integrated dilution air flow into the combustor to attain a predetermined combustion state of the combustor, as shown in step  624 . 
     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 dilution insert. The predetermined combustion state of the combustor also includes a uniform temperature distribution within a primary combustion zone and a 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 a number of 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 has a liner body having a cold side and a hot side, and a dilution passage having a concatenated geometry extending through the liner body, the dilution passage 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 liner of the preceding clause, wherein the second dilution air flow provides a hydraulic support to the first dilution air flow and enhances a penetration of the first dilution air flow into the core primary combustion zone of the combustor. 
     The liner of any preceding clause, wherein the first dilution air flow generates a turbulence in the core primary combustion zone of the combustor and 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 second dilution air flow percolates between a plurality of discrete jets of the first dilution air flow and prevents a development of a high temperature zone in a proximity of the liner and between the plurality of discrete jets. 
     The liner of any preceding clause, wherein the predetermined combustion state of the combustor comprises (i) a reduced temperature in the core primary combustion zone of the combustor, (ii) a compliant NO x  emission level, (iii) a uniform temperature distribution within the core primary combustion zone of the combustor, (iv) a combustor exit temperature profile conforming with a reference temperature profile, (v) an increased mixing of the first dilution air flow and the second dilution air flow with a plurality of combustion products in the core primary combustion zone of the combustor, (vi) a rapid quenching and a quick mixing of the first dilution air flow and the second dilution air flow with a plurality of combustion products in the core primary combustion zone of the combustor, (vii) a predetermined air split ratio of the first dilution air flow and the second dilution air flow, or (viii) any combination thereof. 
     The liner of any preceding clause, wherein the first dilution air flow is ten percent to ninety percent of a total flow through the dilution passage. 
     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 second geometry comprises an annular slot and the first geometry comprises a discrete hole having a semicircular cross section, an elliptical cross section, a race track cross section, or a triangular cross section with one side of the triangular cross section aligned and parallel with the annular slot. 
     The liner of any preceding clause, wherein the first geometry comprises a plurality of discrete holes and the second geometry comprises an annular slot. 
     The liner of any preceding clause, wherein the annular dilution slot is downstream of the plurality of discrete dilution holes. 
     The liner of any preceding clause, wherein the dilution passage comprises a plurality of discrete dilution holes through which flows the first dilution air flow and an annular dilution slot through which flows the second dilution air flow. 
     The liner of any preceding clause, wherein each of the plurality of discrete dilution holes has a first centerline and the annular dilution slot has a second centerline, and wherein the first centerline is parallel with the second centerline. 
     The liner of any preceding clause, wherein the first centerline is offset forward of the second centerline and aligned with a forward surface of the annular dilution slot. 
     The liner of any preceding clause, wherein the first centerline is offset forward of the second centerline and forward of a forward surface of the annular dilution slot. 
     The liner of any preceding clause, wherein the first centerline is offset aft of the second centerline and aligned with an aft surface of the annular dilution slot. 
     The liner of any preceding clause, wherein the first centerline is offset aft of the second centerline and aft of an aft surface of the annular dilution slot. 
     The liner of any preceding clause, wherein the first centerline and the second centerline are angled with respect to an axis normal to the liner. 
     The liner of any preceding clause, wherein the liner body comprises an outer liner and an inner liner, each of the outer liner and the inner liner comprising the dilution passage such that the outer liner comprises an outer liner first dilution air flow and an outer liner second dilution air flow and the inner liner comprises an inner liner first dilution air flow and an inner liner second dilution air flow. 
     The liner of any preceding clause, wherein, in a top view, the outer liner first dilution air flow is offset from the inner liner first dilution air flow. 
     A method of diluting a flow through a combustor including causing a first dilution air flow from a cold side of a combustion liner to a hot side of the combustion liner, causing a second dilution air flow from the cold side of the combustion liner to the hot side of the combustion liner, integrating the first dilution air flow and the second dilution air flow to provide an integrated dilution air flow, injecting the integrated dilution air flow into the combustor to attain a predetermined combustion state of the combustor, generating a turbulence in a core primary combustion zone of the combustor with the first dilution air flow, and filling a region of wakes formed behind the first dilution air flow with the second dilution air flow, wherein the integrated dilution air flow is formed by a concatenated geometry through the combustion liner. 
     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.