Abstract:
A combustor liner with an input end and an output end includes an annular inner wall and an annular outer wall. At least one of the inner wall and outer wall is three-dimensionally contoured. The inner wall and the outer wall form a combustion chamber with the contours creating alternating expanding and constricting regions inside the chamber causing combustion gases to flow in the circumferential and axial directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/202,969, filed Mar. 10, 2014, entitled “3D Non-Axisymmetric Combustor Liner”, by Joel H. Wagner and Paul M. Lutjen, which is a continuation of U.S. patent application Ser. No. 12/709,951, filed on Feb. 22, 2010, now U.S. Pat. No. 8,707,708, issued on Apr. 29, 2014, entitled “3D Non-Axisymmetric Combustor Liner”, by Joel H. Wagner and Paul M. Lutjen, which are incorporated by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    A gas turbine engine extracts energy from a flow of hot combustion gases. Compressed air is mixed with fuel in a combustor assembly of the gas turbine engine, and the mixture is ignited to produce hot combustion gases. The hot gases flow through the combustor assembly and into a turbine where energy is extracted. 
         [0003]    Generally there are an array of fuel nozzles between the compressor and the turbine. One type of combustor is a can combustor. In a can combustor, each fuel nozzle goes into a generally cylindrical combustor can, and one combustor can fuels the combustion process for each fuel nozzle. At the output end of the combustor can comes a concentric heated jet of combustion gases that goes into the turbine and produces work. The combustor may include dilution holes and cooling jets to keep the combustor from melting. 
         [0004]    Another type of combustor is an annular combustor. An annular combustor generally has a liner with an inner wall and an outer wall, and a combustion chamber in between. At the input end (the compressor end) of the combustor, discrete nozzles are placed in an annular shape to inject fuel and air into the combustion chamber. An annular combustor can include dilution holes and/or dilution jets for cooling and mixing within the combustor. It can also include a thermal barrier coating to prevent the combustor from melting. 
       SUMMARY 
       [0005]    A combustor liner with an input end and an output end includes an annular inner wall and an annular outer wall. At least one of the inner wall and outer wall is three-dimensionally contoured. The inner wall and the outer wall form a combustion chamber with the contours creating alternating expanding and constricting regions inside the chamber causing combustion gases to flow in the circumferential and axial directions. 
         [0006]    A method including injecting fuel and air into an annular combustion chamber between inner and outer liner walls of the combustion chamber. It further includes creating localized mixing of the fuel and air in the combustion chamber with three-dimensional contours on at least one of the inner and outer liner walls around the circumference and axially through the length of the combustion chamber, with the contours forming alternating regions of expansion and constriction within the combustor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a cross-sectional view of a gas turbine engine. 
           [0008]      FIG. 2  is an end view of the input end of an annular combustor including a three-dimensionally contoured combustor liner. 
           [0009]      FIG. 3A  is a cross-sectional view of a first embodiment of the combustor of  FIG. 2  from line A-A. 
           [0010]      FIG. 3B  is a cross-sectional view of a first embodiment of the combustor of  FIG. 2  from line B-B. 
           [0011]      FIG. 4A  is a cross-sectional view of a second embodiment of the combustor of  FIG. 2  from line A-A. 
           [0012]      FIG. 4B  is a cross-sectional view of a second embodiment of the combustor of  FIG. 2  from line B-B. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  is a cross-sectional view of gas turbine engine  10 , which includes turbofan  12 , compressor section  14 , combustion section  16  and turbine section  18 . Compressor section  14  includes low-pressure compressor  20  and high-pressure compressor  22 . Air is taken in through fan  12  as fan  12  spins. A portion of the inlet air is directed to compressor section  14  where it is compressed by a series of rotating blades and vanes. The compressed air is mixed with fuel, and is then inserted into combustor section  16  through nozzles and ignited. The combustion exhaust is directed to turbine section  18 . Blades and vanes in turbine section  18  extract energy from the combution exhaust to turn shaft  24  and provide power output for engine  10 . The portion of inlet air that is taken in through fan  12  and not directed through compressor section  14  is bypass air. Bypass air is directed through bypass duct  26  by guide vanes  28 . Some of the bypass air flows through opening  29  to cool combustor section  16 , high pressure compressor  22  and turbine section  18 . 
         [0014]      FIG. 2  shows an end view of an annular combustor  30  at the input end (compressor end), which includes nozzles  32 , combustor liner inner wall  34 , combustor liner outer wall  36  and combustion chamber  37 . Engine center line  38  and dimensions R IE , R OE , R IC , R OC , D E  and D C  are also shown. Nozzles  32  generally are evenly spaced between liner inner wall  34  and liner outer wall  36 . Liner inner wall  34  and liner outer wall  36  can be made with cobalt or a nickel alloy and may include a thermal barrier coating. Liner inner and outer walls  34 ,  36  include three-dimensional contours around the circumference of the inner and outer walls  34 ,  36  and three-dimensional contours axially through length of the combustion chamber  37  from the input to the output. The three-dimensional contours are generally in a wavelike pattern forming alternating regions of constriction and expansion in combustion chamber  37 . The contours around the circumference at the input end of combustor  30  can be seen from the view shown in  FIG. 2 . At the input end of combustor  30 , the contours around the circumference of liner walls  34 ,  36  form regions of expansion at nozzles  32  and regions of constriction between nozzles  32 . R IE  is the distance from engine center line  38  to liner inner wall  34  at a region of expansion. R OE  is the distance from engine center line to liner outer wall  36  at a region of expansion. R IC  is the distance from engine center line  38  to liner inner wall  34  at a region of constriction. R OC  is the distance from engine center line to liner outer wall  36  at a region of constriction. D E  is the distance between liner inner wall  34  and liner outer wall  36  at a region of expansion (R OE -R IE ). D C  is the distance between liner inner wall  34  and liner outer wall  36  at a region of constriction (R OC -R IC ). The contours of liner inner wall  34  and liner outer wall  36  generally mirror each other, and can be of the size that D C  (the distance from liner inner wall  34  to liner outer wall  36  at a region of constriction) is about ⅓ to about ⅗ of D E  (the distance from liner inner wall  34  to liner outer wall  36  at a region of expansion), but may be more or less depending on the needs of the particular combustor. 
         [0015]    Each nozzle  32  distributes compressed air and fuel into combustor  30 , between liner inner wall  34  and liner outer wall  36 . The air and fuel distributed is a mixture set for flame holding to promote combustion within the combustion chamber  37 . This distribution by nozzles  32  results in very intense heat at each discrete nozzle  32 . 
         [0016]    When exiting combustor  30 , the combusted fuel and air mixture enters turbine section  18  where it comes into contact with first stage high pressure turbine (“HPT”) vanes (see  FIG. 1 ). Circumferential variation in the temperature entering turbine  18  leads to variation in distress observed by static hardware in turbine  18 . Advanced distress of turbine hardware at a single circumferential location can limit service life of the engine, or time between overhauls. Thus, to maximize service life, a circumferentially prescribed or uniform temperature profile is desirable. Mixing of the air and fuel axially through the length of combustor  30  from input to output can promote a more uniform distribution of temperature (as well as pressure and species) at the output of combustor  30 . This uniform distribution of temperature going into the turbine helps to ensure that the progression of distress on turbine hardware is not dependent on circumferential location. 
         [0017]    The current invention controls the mixing by adding three-dimensional contours circumferentially and axially through the length of combustor  30  liner inner wall  34  and liner outer wall  36  to form alternating regions of constriction and expansion within combustion chamber  37 . In previous combustion chambers, mixing was often done by adding dilution holes or jets to combustor liner walls  34 ,  36 . Dilution holes are holes in liner walls which allow cooler air into the combustor to promote mixing. Dilution jets propel air into the combustor at high velocity to promote mixing in the combustor. The current invention further promotes mixing and controls the flow in combustor  30  by adding three-dimensional contours circumferentially and axially through the length of combustor  30  liner inner wall  34  and liner outer wall  36  to form alternating regions of constriction and expansion within combustion chamber  37 . 
         [0018]      FIG. 3A  is a cross-sectional view of a first embodiment of the combustor of  FIG. 2  above engine center line  38  from line A-A (at nozzle  32 ) of  FIG. 2 .  FIG. 3A  includes nozzle  32 , three-dimensionally contoured liner inner wall  34   a,  three-dimensionally contoured liner outer wall  36   a,  combustion chamber  37 , input end  40 , output end  42 , nozzle center line of flow  44 , regions of expansion E and a region of constriction C. Dimensions R IE  (from engine centerline  38  to liner inner wall  34   a  at a region of expansion), R OE  (from engine centerline  38  to liner outer wall  36   a  at a region of expansion), R IC  (from engine centerline  38  to liner inner wall  34   a  at a region of constriction), R OC  (from engine centerline  38  to liner outer wall  36   a  at a region of constriction), D E  (between liner inner wall  34   a  and liner outer wall  36   a  at a region of expansion, R OE -R IE ) and D C  (between liner inner wall  34   a  and liner outer wall  36   a  at a region of constriction, R OC -R IC ) for regions of expansion and constriction are also shown. 
         [0019]    An air and fuel mixture is injected into combustion chamber  37  at input end  40  by nozzle  32  at center line of flow  44 . This mixture is ignited and travels through combustor to output end  42 . As mentioned above, this results in very intense heat downstream of each discrete nozzle  32 . To help disburse this heat and control overall mixing, liner inner wall  34   a  and outer wall  36   a  include three-dimensional contours both circumferentially and axially through the length of combustor  30  from input  40  to output  42  to form alternating regions of constriction C and expansion E. These alternating regions of constriction C and expansion E force combustion gases to move circumferentially as well as axially after being injected into combustion chamber  37 . 
         [0020]    Contoured liner inner wall  34   a  and liner outer wall  36   a  illustrate contours axially through the length of combustor liner at a cross-section where a nozzle  32  is located. Liner inner wall  34   a  and liner outer wall  36   a  form a region of expansion E at input  40 . Moving axially toward output  42 , liner inner wall  34   a  and liner outer wall  36   a  form a region of constriction C, and then another region of expansion E (in a wavelike pattern). Where the contours bring liner walls together to form a region of constriction C, inner liner wall  34   a  and outer liner wall  36   a  generally mirror each other, and each liner wall ( 34   a,    36   a ) can come toward the other about ⅙ to about 1/10 of the distance of D E  (the distance between liner inner wall  34   a  and liner outer wall  36   a  at an expansion region). This results in D C  (the distance between liner inner wall  34   a  and liner outer wall  36   a  at a constriction region C) being about ⅓ to about ⅗ of D E . 
         [0021]    When liner inner wall  34   a  and liner outer wall  36   a  go from an expansion region E (at input  40 ) to a constriction region C, some of the flow is forced to move circumferentially within combustion chamber  37  toward circumferentially adjacent expansion zones (such as expansion region E in  FIG. 3B ). This circumferential flow draws the hot air and fuel mixture distributed by nozzle  32  to areas not directly in front of a nozzle  32 , promoting redistribution of combustion gases in less hot areas (areas not directly in front of a nozzle  32 ). 
         [0022]      FIG. 3B  is a cross-sectional view of a first embodiment of the combustor of  FIG. 2  above engine center line  38  from line B-B (between nozzles) of  FIG. 2 .  FIG. 3B  includes three-dimensionally contoured liner inner wall  34   b,  three-dimensionally contoured liner outer wall  36   b,  combustion chamber  37 , input end  40 , output end  42 , and regions of constriction C and a region of expansion E.  FIG. 3B  further includes dimensions R 3  (from engine centerline  38  to liner inner wall  34   b  at a region of expansion), R OE  (from engine centerline  38  to liner outer wall  36   b  at a region of expansion), R IC  (from engine centerline  38  to liner inner wall  34   b  at a region of constriction), R OC  (from engine centerline  38  to liner outer wall  36   b  at a region of constriction), D E  (between liner inner wall  34   b  and liner outer wall  36   b  at a region of expansion, R OE -R IE ) and D C  (between liner inner wall  34   b  and liner outer wall  36   b  at a region of constriction, R OC -R IC ). 
         [0023]    Contoured liner inner wall  34   b  and liner outer wall  36   b  illustrate contours axially through the length of combustor liner at a cross-section between where nozzles  32  are located. As can be seen in  FIG. 3B , cross-sections between nozzles  32  at input  40  of combustion chamber  37  start with a region of constriction C, followed by a region of expansion E, and then another region of constriction C. As in  FIG. 3B , inner liner wall  34   b  and outer liner wall  36   b  generally mirror each other, and each liner wall ( 34   b,    36   b ) can be come toward the other about ⅙ to about 1/10 of the distance of D E  (the distance between liner inner wall  34   b  and liner outer wall  36   b  at an expansion region E). This results in D C  (the distance between liner inner wall  34   b  and liner outer wall  36   b  at a constriction region C) being about ⅓ to about ⅗ of D E . The zones of constriction and expansion in  FIG. 3B  also work to force a circumferential flow of the gases within combustion chamber  37 , thereby promoting mixing and a more even distribution of temperature, pressure and species in combustor  30  as gases move from input  40  to output  42 . 
         [0024]    The cross-sections in  FIG. 3A  and in  FIG. 3B  are circumferentially next to each other and work together to promote mixing. As can be seen from  FIGS. 3A-3B , when the inner and outer liner walls of  FIG. 3A  form a region of constriction, the inner and outer liner walls of  FIG. 3B  form a region of expansion (and vice versa). For example, at combustor  30  input  40 ,  FIG. 3A  liner walls  34   a,    36   a  form a region of expansion and  FIG. 3B  liner walls  34   b,    36   b  form a region of constriction. When liner walls in a cross-section go from forming a region of expansion to a region of constriction, the combustion gases will not all be able to travel axially, and some will be forced to travel circumferentially due to the constriction. For example, in  FIG. 3A  at input  40  liner walls  34   a,    36   a  form a region of expansion, and at the midpoint between input  40  and output  42  liner walls  34   a,    36   a  form a region of constriction. As combustion gases travel axially from the zone of expansion to the zone of constriction, some of the gases will be forced to move circumferentially to the region of expansion shown in  FIG. 3B  at the midpoint between input  40  and output  42 . Then as the region of expansion formed by liner walls  34   b,    36   b  in  FIG. 3B  goes into a region of constriction near output  42 , combustion gases are forced to move circumferentially again to a region of expansion in a neighboring cross-section. This circumferential flow controls mixing and can result in a more even or a prescribed distribution of temperature, pressure and species in combustor  30  as the air and fuel mixture moves axially between input  40  and output  42 . Contoured liner walls  34 ,  36  can also include dilution holes and/or dilution jets (discussed in relation to  FIG. 2 ) to further promote mixing in and aid in cooling combustor  30 . 
         [0025]    The size and placement of contours on liner inner walls  34  and liner outer walls  36  are shown for example purposes only and may be varied according to combustor needs. Generally, the scale of contours is proportional to the combustor velocity, the velocity at which the fuel and air mixture is distributed from nozzles  32 . For example, in a combustor where nozzle  32  distributes air and fuel into combustor  30  at a low velocity (about 0.1 mach), contours which form regions of constriction would have to be larger to promote mixing and control the flow direction (for example, D C  can be about ⅓ of D E ) than if nozzle  32  has a higher velocity. If nozzle  32  distributes air and fuel at a high velocity (about 0.3 mach) contours could be smaller (for example, D C  can be about ⅗ of D E ). 
         [0026]      FIG. 4A  illustrates a cross-section of a second embodiment of the combustor of  FIG. 2  from line A-A of  FIG. 2 , having a three-dimensionally contoured liner, with the combustor having a variation in volume from input  40  to output  42 , specifically a decrease in volume. Combustor  30  includes nozzle  32 ; three-dimensionally contoured liner inner wall  34 ′; three-dimensionally contoured liner outer wall  36 ′; combustion chamber  37 ; input end  40 ; output end  42 ; nozzle center line of flow  44 ; axial zones F, G and H; and dimensions D FE  (from inner liner wall  34 ′ to outer liner wall  36 ′ at expansion region E in zone F), D GC  (from inner liner wall  34 ′ to outer liner wall  36 ′ at constriction region C in zone G), and D HE  (from inner liner wall  34 ′ to outer liner wall  36 ′ at expansion region E in zone H). 
         [0027]      FIG. 4B  illustrates a cross-section of a second embodiment of the combustor of  FIG. 2  from line B-B (between nozzles) of  FIG. 2 .  FIG. 4B  includes three-dimensionally contoured liner inner wall  34 ′; three-dimensionally contoured liner outer wall  36 ′; combustion chamber  37 ; input end  40 ; output end  42 ; axial zones F, G, and H; and distance measurements D FC  (from inner liner wall  34 ′ to outer liner wall  36 ′ at constriction region C in zone F), D GE  (from inner liner wall  34 ′ to outer liner wall  36 ′ at expansion region E in zone G), and D HC  (from inner liner wall  34 ′ to outer liner wall  36 ′ at constriction region C in zone H). 
         [0028]    Combustor  30 , contoured liner inner walls  34 ′ and contoured liner outer walls  36 ′ work much the same way as discussed in relation to  FIGS. 3A-3B , moving flow circumferentially and mixing combustion gases from input  40  to output  42 . However, in this embodiment, the combustion chamber  37  experiences a decrease in volume from input  40  to output  42  (as shown through cross-sections F, G, H losing area from input  40  to output  42 ). Therefore, the distance measurements between liner inner wall  34 ′ and liner outer wall  36 ′ for areas of expansion E are largest in zone F (D FE  in  FIG. 4A ), smaller in zone G (D GE  in  FIG. 4B ), and smallest in zone H (D HE  in  FIG. 4A ). 
         [0029]    As the cross-sectional area (and total overall volume) of combustion chamber  37  decreases from input  40  to output  42 , this decrease in area would increase the velocity of the combustion gases. As mentioned above, the scale of contours to form regions of constriction C is approximately inversely proportional to the velocity of the combustion gases. Smaller contours (meaning the distance D C  between inner liner wall  34 ′ and outer liner wall  36 ′ is larger in regions of constriction C) can promote mixing when velocity is higher, whereas larger contours (meaning the distance D C  between inner liner wall  34 ′ and outer liner wall  36 ′ is smaller in regions of constriction C) are necessary to promote the same levels of mixing when velocity is lower. Therefore, as the velocity increases from input  40  to output  42  due to the decrease in combustion chamber  37  volume or the addition of dilution and cooling air, the contours forming constriction regions C on liner inner wall  34 ′ and liner outer wall  36 ′ can decrease while still promoting the same levels of mixing. In some combustors, axially through the length from input  40  to output  42  of combustor  30 , the contours may diminish to zero or to small values as that might be needed for controlling the flow into the HPT vane (making dimensions D E  and D C  about equal). 
         [0030]    In summary, the current invention adds three-dimensional contouring of inner and outer liner walls in a combustor to form alternating regions of constriction and expansion both circumferentially and axially to better control flow coming out of the combustor into the turbine. By controlling flow to promote mixing, an even or prescribed distribution of temperature, pressure and species at the output of the combustor can be achieved. This can prolong engine life by preventing the advanced distress of turbine hardware due to hot spots flowing out of the combustor and into the turbine. This mixing can also promote more efficient combustion in the combustor. The three-dimensional contours may allow for the elimination of some or all dilution holes and/or dilution jets in the combustor liner (previously used to promote mixing). 
         [0031]    While the invention has been discussed mainly in reference to promoting and controlling mixing as a means to achieve an even distribution of temperature, pressure and species at the output of the combustor, the three-dimensionally contoured liner could be used in situations where an even distribution is not desired. The three-dimensional wavelike contours forming regions of constriction and expansion can be placed throughout the combustor liner inner wall and liner outer wall to control flow and/or promote mixing in any way desired. While this invention has been discussed mainly in reference to liner inner and liner outer walls each having three-dimensional contours, controlling of the flow and/or mixing can also be done by having three-dimensional contours only on liner inner wall or liner outer wall. 
         [0032]    While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.