Patent Publication Number: US-2007119183-A1

Title: Gas turbine engine combustor

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates generally to combustors, and more particularly to a gas turbine engine combustor.  
      Conventional gas turbine engine combustors have outer and inner annular cases, outer and inner liners (with air dilution holes) located radially between the outer and inner annular cases, a combustor dome connecting the outer and inner liners, and circumferentially arrayed premixer tubes each having an entrance and an exit. Each premixer tube is adapted to receive fuel-injector-discharged fuel, the entrance is adapted to receive at least some compressor-discharge air, and the exit is aligned to axially deliver such fuel-air mixture for ignition in the combustor. The combustion gases power a downstream turbine which rotates the compressor. Straight flow and reverse flow combustors are known. Gas turbine engines have been used to power aircraft, ships, etc.  
      Still, scientists and engineers continue to seek improved gas turbine engine combustors.  
     BRIEF DESCRIPTION OF THE INVENTION  
      A first expression of a first embodiment of the invention is a gas turbine engine combustor including a gas-turbine-engine-combustor outer annular case and a gas-turbine-engine-combustor premixer tube. The outer annular case has a longitudinal axis. The premixer tube has an entrance, an exit, and a centerline. The premixer tube is adapted to receive fuel-injector-discharged fuel. The entrance is adapted to receive at least some compressor-discharge air. The exit is located inside the outer annular case. At the exit the centerline points in a direction which is more perpendicular to, than parallel to, the longitudinal axis.  
      A second expression of a first embodiment of the invention is a gas turbine engine combustor including a straight-flow-combustor outer annular case and a gas-turbine-engine-combustor premixer tube. The outer annular case has a longitudinal axis. The premixer tube has an entrance, an exit, and a centerline. The premixer tube is adapted to receive fuel-injector-discharged fuel. The entrance is adapted to receive at least some compressor-discharge air. The exit is located inside the outer annular case. At the exit the centerline points in a direction which is more perpendicular to, than parallel to, the longitudinal axis. The direction is angled between generally sixty degrees and generally eighty degrees away from the longitudinal axis.  
      A first expression of a second embodiment of the invention is a gas turbine engine combustor including a reverse-flow-combustor outer annular case and a gas-turbine-engine-combustor premixer tube. The outer annular case has a longitudinal axis. The premixer tube has an entrance, an exit, and a centerline. The premixer tube is adapted to receive fuel-injector-discharged fuel. The entrance is adapted to receive at least some compressor-discharge air. The exit is located inside the outer annular case. At the exit the centerline points in a direction which is more perpendicular to, than parallel to, the longitudinal axis. The direction is angled between generally sixty degrees and generally eighty degrees away from the longitudinal axis.  
      In one example of any expression of any embodiment of the invention, use of a premixer tube whose centerline, at the exit of the premixer tube, points in a direction more perpendicular to, than parallel to, the longitudinal axis of the gas-turbine-engine-combustor outer annular case creates a swirled flow from the exit of the premixer tube. In this example, such swirled flow results in a shorter and simpler combustor design with fewer swirlers, lower soot, lower carbon monoxide, lower NOx, a greater turndown (e.g., 20:1), an excellent pattern factor (e.g., less than 0.20), and a lower cost compared to the axial flow from the exit of a premixer tube of a conventional gas-turbine-engine combustor.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings illustrate two embodiments of the invention wherein:  
       FIG. 1  is a schematic front elevational view looking downstream of a first embodiment of a gas turbine engine combustor, wherein the combustor is a straight-flow combustor, and includes a premixer tube and additional premixer tubes;  
       FIG. 2  is a schematic aft elevational view looking upstream of the combustor of  FIG. 1 ;  
       FIG. 3  is a cross sectional view taken along lines  3 - 3  of  FIG. 2  with the tubes not shown in cross section for clarity;  
       FIG. 4  is an enlarged cross sectional view of the premixer tube of the combustor of  FIG. 1  with a fuel injector present;  
       FIG. 5  is a schematic cross sectional view of a second embodiment of a gas turbine engine combustor, wherein the combustor is a reverse-flow combustor, and includes a premixer tube with the tube not shown in cross section for clarity;  
       FIG. 6  is a cross-sectional view taken along lines  5 - 5  of  FIG. 4  showing additional premixer tubes and with the fuel injectors omitted for clarity, and  
       FIG. 7  is an enlarged perspective view of the premixer tube of the combustor of  FIG. 5  with a fuel injector present. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring now to the drawings,  FIGS. 1-4  disclose a first embodiment of the invention. A first expression of the embodiment of  FIGS. 1-4  is for a gas turbine engine combustor  110  including a gas-turbine-engine-combustor outer annular case  112  and a gas-turbine-engine-combustor premixer tube  114 . The outer annular case  112  has a longitudinal axis  116 . The premixer tube  114  has an entrance  118 , an exit  120 , and a centerline  122 . The premixer tube  114  is adapted to receive fuel-injector-discharged fuel  124 . The entrance  118  is adapted to receive at least some compressor-discharge air  126 . The exit  120  is disposed inside the outer annular case  112 . At the exit  120  the centerline  122  points in a direction  128  which is more perpendicular to, than parallel to, the longitudinal axis  116 .  
      In one enablement of the first expression of the first embodiment of  FIGS. 1-4 , the direction  128  is more perpendicular to, than along, a reference line  130  which extends from the centerline  122  at the exit  120  to the longitudinal axis  116 . In one variation, the direction  128  is angled between generally sixty degrees and generally eighty degrees away from the longitudinal axis  116  (i.e., away from a line parallel to the longitudinal axis  116  and intersecting the centerline  122  at the exit  120 ), and the direction  128  is angled between generally sixty degrees and generally eighty degrees away from the reference line  130 .  
      In one implementation of the first expression of the first embodiment of  FIGS. 1-4 , the combustor  110  also includes a gas-turbine-engine-combustor inner annular case  132 , a gas-turbine-engine-combustor outer liner  134 , and a gas-turbine-engine-combustor inner liner  136 , wherein the outer and inner liners  134  and  136  are disposed radially between the outer and inner annular cases  112  and  132  and wherein the exit  120  is disposed radially between the outer and inner liners  134  and  136 . In one variation, the combustor  110  also includes a plurality of gas-turbine-engine-combustor additional premixer tubes  138  substantially identical to the premixer tube  114 , wherein the premixer and additional premixer tubes  114  and  138  are substantially circumferentially arrayed with a substantially equal circumferential distance between adjacent ones of the exits  120  of the premixer and additional premixer tubes  114  and  138 . In one modification, the exits  120  of the premixer and additional premixer tubes  114  and  138  are disposed wherein ignition at one of the exits  120  of the premixer and additional premixer tubes  114  and  138  will cause ignition, in sequential rotation, at each of the other of the exits  120  of the premixer and additional premixer tubes  114  and  138 .  
      In one application of the first expression of the first embodiment of  FIGS. 1-4 , the outer and inner liners  134  and  136  each include a plurality of air dilution holes  140 . In one employment, the combustor  110  also includes a combustor dome  142  connecting the outer and inner liners  134  and  136 . In one construction, the premixer tube  114  is a thermal-barrier-coated tube and the combustor dome  142  is a thermal-barrier-coated combustor dome.  
      In one deployment of the first expression of the first embodiment of  FIGS. 1-4 , some compressor-discharge air  144  also flows between the outer annular case  112  and the outer liner  134  and between the inner annular case  132  and the inner liner  136 . In one variation, some of that compressor-discharge air  144  flows through the air dilution holes  140 . In a gas turbine engine, a compressor (not shown) upstream of the combustor  110  supplies the compressor-discharge air  126  and  144  to the combustor  110  and combustion gases from the combustor  110  are channeled to a downstream turbine (not shown) which rotates the compressor as is known to those skilled in the art. Examples of uses of the combustor  110  include, without limitation, aircraft gas turbine engines, helicopter gas turbine engines, land-based gas turbine engines such as electric-power-plant gas turbine engines, and marine-base gas turbine engines such as ship-propulsion gas turbine engines, etc. In one arrangement, the premixer tube  114  is equipped with some swirlers (not shown). In one arrangement, a fuel injector  146  discharges fuel in the premixer tube  114  proximate the exit  120 . Fuel types include natural and/or synthetic liquid fuels and/or natural and/or synthetic gaseous fuels.  
      Designs of the first expression of the first embodiment of  FIGS. 1-4  include straight flow and reverse flow can types and straight flow and reverse flow non-can type combustor arrangements. In one non-can type combustor arrangement, a gas turbine engine has a single combustor (annular combustor) whose centerline is substantially coaxial with the compressor and turbine centerlines. In one can type combustor arrangement, a gas turbine engine has a plurality of annularly arrayed can combustors (can-annular combustors) whose centerlines are angled with respect to the compressor and turbine centerlines. It is noted that each premixer tube of a combustor need not be of the same size and/or operate at the same fuel-to-air ratio and/or receive the same amount of compressor-discharged air.  
      In one example of the first expression of the first embodiment of  FIGS. 1-4 , the direction  128  forms an angle less than generally thirty degrees to a plane (the plane of the paper in  FIG. 2 ) which is perpendicular to the longitudinal axis  116  and passes through the centerline  122  at the exit  120 , and the direction  128  forms an angle less than generally thirty degrees to a tangent at a point on a circle which passes through the intersection of the centerline  122  and the exit  120  of the premixer and additional premixer tubes  114  and  138 ) wherein the point is such intersection.  
      It is noted that the first combustor embodiment of  FIGS. 1-4  illustrates an embodiment of a straight-flow combustor, that the second combustor embodiment of  FIGS. 5-7  illustrates an embodiment of a reverse-flow combustor, and that the above description of the first embodiment is equally applicable to describing the second embodiment with the substitution of the 200 series of part numbers shown in  FIGS. 5-7  in place of the 100 series of part numbers shown in  FIGS. 1-4 .  
      A second expression of the first embodiment of  FIGS. 1-4  is for a gas turbine engine combustor  110  including a straight-flow-combustor outer annular case  112 ′ and a gas-turbine-engine-combustor premixer tube  114 . The outer annular case  112 ′ has a longitudinal axis  116 . The premixer tube  114  has an entrance  118 , an exit  120 , and a centerline  122 . The premixer tube  114  is adapted to receive fuel-injector-discharged fuel  124 . The entrance  118  is adapted to receive at least some compressor-discharge air  126 . The exit  120  is disposed inside the outer annular case  112 ′. At the exit  120  the centerline  122  points in a direction  128  which is more perpendicular to, than parallel to, the longitudinal axis  116 . The direction  128  is angled between generally sixty degrees and generally eighty degrees away from the reference line  130 .  
      In one enablement of the second expression of the first embodiment of  FIGS. 1-4 , the direction  128  is more perpendicular to, than along, a reference line  130  which extends from the centerline  122  at the exit  120  to the longitudinal axis  116 . In one variation, the direction  128  is angled between generally sixty degrees and generally eighty degrees away from the reference line  130 .  
      In one implementation of the second expression of the first embodiment of  FIGS. 1-4 , the combustor  110  also includes a straight-flow-combustor inner annular case  132 ′, a gas-turbine-engine-combustor outer liner  134 , and a gas-turbine-engine-combustor inner liner  136 , wherein the outer and inner liners  134  and  136  are disposed radially between the outer and inner annular cases  112 ′ and  132 ′ and wherein the exit  120  is disposed radially between the outer and inner liners  134  and  136 . In one variation, the combustor  110  also includes a plurality of gas-turbine-engine-combustor additional premixer tubes  138  substantially identical to the premixer tube  114 , wherein the premixer and additional premixer tubes  114  and  138  are substantially circumferentially arrayed with a substantially equal circumferential distance between adjacent ones of the exits  120  of the premixer and additional premixer tubes  114  and  138 . In one modification, the exits  120  of the premixer and additional premixer tubes  114  and  138  are disposed wherein ignition at one of the exits  120  of the premixer and additional premixer tubes  114  and  138  will cause ignition, in sequential rotation, at each of the other of the exits  120  of the premixer and additional premixer tubes  114  and  138 .  
      A first expression of the second embodiment of  FIGS. 5-7  is for a gas turbine engine combustor  210  including a reverse-flow-combustor outer annular case  212 ′ and a gas-turbine-engine-combustor premixer tube  214 . The outer annular case  212 ′ has a longitudinal axis  216 . The premixer tube  214  has an entrance  218 , an exit  220 , and a centerline  222 . The premixer tube  214  is adapted to receive fuel-injector-discharged fuel  224 . The entrance  218  is adapted to receive at least some compressor-discharge air  226 . The exit  220  is disposed inside the outer annular case  212 ′. At the exit  220  the centerline  222  points in a direction  228  which is more perpendicular to, than parallel to, the longitudinal axis  216 . The direction  228  is angled between generally sixty degrees and generally eighty degrees away from the reference line  230 .  
      In one enablement of the first expression of the second embodiment of  FIGS. 5-7 , the direction  228  is more perpendicular to, than along, a reference line  230  which extends from the centerline  222  at the exit  220  to the longitudinal axis  216 . In one variation, the direction  228  is angled between generally sixty degrees and generally eighty degrees away from the reference line  230 .  
      In one implementation of the first expression of the second embodiment of  FIGS. 5-7 , the combustor  210  also includes a reverse-flow-combustor inner annular case  232 ′, a gas-turbine-engine-combustor outer liner  234 , and a gas-turbine-engine-combustor inner liner  236 , wherein the outer and inner liners  234  and  236  are disposed radially between the outer and inner annular cases  212 ′ and  232 ′ and wherein the exit  220  is disposed radially between the outer and inner liners  234  and  236 . In one variation, the combustor  210  also includes a plurality of gas-turbine-engine-combustor additional premixer tubes  238  substantially identical to the premixer tube  214 , wherein the premixer and additional premixer tubes  214  and  238  are substantially circumferentially arrayed with a substantially equal circumferential distance between adjacent ones of the exits  220  of the premixer and additional premixer tubes  214  and  238 . In one modification, the exits  220  of the premixer and additional premixer tubes  214  and  238  are disposed wherein ignition at one of the exits  220  of the premixer and additional premixer tubes  214  and  238  will cause ignition, in sequential rotation, at each of the other of the exits  220  of the premixer and additional premixer tubes  214  and  238 . In one example, not shown, the premixer and additional premixer tubes have entrances disposed between the outer annular case and the outer liner, have mid portions which loop outside and then re-enter the outer annular case, and have exits disposed between the outer and inner liners.  
      While the present invention has been illustrated by a description of several expressions of embodiments, it is not the intention of the applicant to restrict or limit the spirit and scope of the appended claims to such detail. Numerous other variations, changes, and substitutions will occur to those skilled in the art without departing from the scope of the invention.