Patent Publication Number: US-10309654-B2

Title: Structure for cooling gas turbine engine

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a structure for cooling a gas turbine engine in which an open flange part encircling a fuel supply hole formed in a combustor of the gas turbine engine comprises a conical portion that enlarges in a conical shape in going toward an outside of the combustor and a flat portion that extends radially outward in a flat plate shape from an extremity of the conical portion, and a nozzle guide comprises a cylindrical portion that covers an outer periphery of a fuel nozzle for supplying fuel to the fuel supply hole and a bottom flange portion that is bent radially outward from a corner portion at an extremity of the cylindrical portion and is supported in a floating state on the flat portion. 
     Description of Related Art 
     Japanese Patent Application Laid-open No. 4-244513 has made known an arrangement that enables a constant amount of air to flow in a gap between a support plate  50  (open flange part) and a fuel injection nozzle  32  (fuel nozzle) fitted into a ferrule  58  (nozzle guide), even when the fuel injection nozzle  32  moves relative to the support plate  50 , by welding a retaining plate  74  (cap) to extremities of elliptical flanges  70   a  to  70   d  projectingly provided on the support plate  50  encircling a dome inlet  28  (fuel supply hole) of a combustor  10  and by supporting the ferrule  58  in a floating state in a space formed between the support plate  50  and the retaining plate  74 . 
     When an open flange part encircling a fuel supply hole formed in a combustor of a gas turbine engine includes a conical portion and a flat portion, a nozzle guide supporting a fuel nozzle for supplying fuel to the fuel supply hole includes a cylindrical portion and a bottom flange portion, and the open flange part and the fuel nozzle are cooled with air for cooling that is supplied via a cooling hole formed in the bottom flange portion of the nozzle guide, as described in detail in the ‘DESCRIPTION OF THE PREFERRED EMBODIMENT’ section of the present Specification, if an axial height of the fuel nozzle of the open flange part is decreased in order to achieve a lightening of weight, the cooling hole in the bottom flange portion of the nozzle guide is blocked by the flat portion of the open flange part, and there is a possibility that it will become difficult to supply air for cooling via the cooling hole. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished in light of the above circumstances, and it is an object thereof to enable air for cooling to be reliably supplied via a cooling hole formed in a nozzle guide while achieving a lightening of weight by decreasing an axial height of a fuel nozzle of an open flange part. 
     In order to achieve the object, according to a first aspect of the present invention, there is provided a structure for cooling a gas turbine engine in which an open flange part encircling a fuel supply hole formed in a combustor of the gas turbine engine comprises a conical portion that enlarges in a conical shape in going toward an outside of the combustor and a flat portion that extends radially outward in a flat plate shape from an extremity of the conical portion, and a nozzle guide comprises a cylindrical portion that covers an outer periphery of a fuel nozzle for supplying fuel to the fuel supply hole and a bottom flange portion that is bent radially outward from a corner portion at an extremity of the cylindrical portion and is supported in a floating state on the flat portion, wherein a cooling hole for supplying air that cools the open flange part and the fuel nozzle is formed in the corner portion of the nozzle guide, and a direction of the cooling hole is inclined toward an axis of the fuel nozzle. 
     In accordance with the first aspect, the open flange part encircling the fuel supply hole formed in the combustor of the gas turbine engine includes the conical portion that enlarges in a conical shape in going toward the outside of the combustor and the flat portion that extends radially outward in a flat plate shape from the extremity of the conical portion, and the nozzle guide includes the cylindrical portion that covers the outer periphery of the fuel nozzle for supplying fuel to the fuel supply hole and the bottom flange portion that is bent radially outward from the corner portion at the extremity of the cylindrical portion and is supported in a floating state on the flat portion. Since the cooling hole for supplying air that cools the open flange part and the fuel nozzle is faulted in the corner portion of the nozzle guide, and the direction of the cooling hole is inclined toward the axis of the fuel nozzle, even when the axial height of the fuel nozzle of the open flange part is decreased so as to achieve a lightening of weight, it is possible to avoid blocking of the cooling hole of the nozzle guide by the flat portion and, moreover, since the radial dimension of the flat portion can be reduced by an amount corresponding to the cooling hole due to its absence, it becomes possible to further lighten the weight. 
     According to a second aspect of the present invention, in addition to the first aspect, the direction of the cooling hole is inclined in a circumferential direction with the axis of the fuel nozzle as a center. 
     In accordance with the second aspect, since the direction of the cooling hole is inclined in a circumferential direction with the axis of the fuel nozzle as the center, a swirl flow due to air supplied from the outer peripheral part of the fuel nozzle to the combustor is assisted by a swirl flow generated by air supplied via the cooling hole in the corner portion of the nozzle guide, thus enabling stable combustion of an air-fuel mixture in the combustor. 
     According to a third aspect of the present invention, in addition to the first or second aspect, the nozzle guide is a press-formed product. 
     In accordance with the third aspect, since the nozzle guide is a press-formed product, it is possible to reduce the cost compared with a case in which the nozzle guide is produced by machining. 
     The above and other objects, characteristics and advantages of the present invention will be clear from detailed descriptions of the preferred embodiment which will be provided below while referring to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  to  FIG. 5C  show an embodiment of the present invention: 
         FIG. 1  is a longitudinal sectional view of a combustor of a gas turbine engine; 
         FIG. 2  is an enlarged view of part  2  in  FIG. 1 ; 
         FIG. 3  is a view in the direction of arrow  3  in  FIG. 1 ; 
         FIG. 4  is a view in the direction of arrow  4  in  FIG. 1 ; and 
         FIG. 5A  to  FIG. 5C  are diagrams for comparison between a comparative example and the embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention is explained below by reference to  FIG. 1  to  FIG. 5C . 
     As shown in  FIG. 1 , a combustor  11  disposed so as to encircle an engine axis of a gas turbine engine includes an annular combustor main body part  12  and a dome part  13  blocking one end part of the combustor main body part  12 . A plurality of open flange parts  14  are disposed, at equal intervals on a circumference having the engine axis as the center, on the semicircular cross section dome part  13 , and the extremities of fuel nozzles  15  for injecting fuel into the interior of the combustor  11  via fuel supply holes  13   a  formed in the center of the open flange parts  14  are covered with a nozzle guide  22  supported in a floating state by nozzle guide support means  16 . Furthermore, a plurality of spark plug fitting holes  12   a  are formed in an outer peripheral wall of the combustor main body part  12  at equal intervals in the circumferential direction, and the extremities of spark plugs  18  are inserted into spark plug support collars  23  supported in a floating state by spark plug support means  17  provided on the spark plug fitting holes  12   a . The fuel nozzle  15  includes an air supply hole encircling the periphery of the fuel injection hole, and air passing through the air supply hole is supplied into the interior of the combustor  11  via the periphery of the fuel injection hole in a swirl flow. 
     The combustor  11  is cantilever-supported on a casing of the gas turbine engine via an inner peripheral part thereof, and since base end parts of the fuel nozzles  15  and the spark plugs  18  are cantilever-supported on the casing, the fuel nozzles  15  and the spark plugs  18  move relative to the combustor  11  due to a difference in the amount of thermal expansion of each part accompanying change in temperature of the gas turbine engine. In order to allow this relative movement, the extremities of the fuel nozzles  15  are covered with the nozzle guide  22  supported on the nozzle guide support means  16  in a floating state, and the extremities of the spark plugs  18  are inserted into spark plug support collars  23  supported by the spark plug support means  17  in a floating state. Formed in the outer peripheral wall and an inner peripheral wall of the combustor main body part  12  are a plurality of air inlet holes  12   b  for introducing air for combustion into the interior of the combustor  11 . 
     The structure of the nozzle guide support means  16  is now explained by reference to  FIG. 2  to  FIG. 4 . 
     The open flange part  14  of the combustor  11  includes a conical portion  14   a  that enlarges in a conical shape from the outer periphery of the fuel supply hole  13   a  along an axis L of the fuel nozzle  15 , a flat portion  14   b  that extends from the extremity of the conical portion  14   a  radially outward with respect to the axis L, and two projecting portions  14   c  that project radially outward from two positions, having the axis L interposed therebetween, at the radially outer ends of the flat portion  14   b , rivet holes  14   d  extending through extremities of the projecting portions  14   c . A cylindrical spacer  19  and a cap  20  formed by bending a plate material are superimposed on the projecting portion  14   c  and are fixed by swaging the extremity of a rivet  21  extending in the axis L direction through a rivet hole  20   a  of the cap  20 , the spacer  19 , and the rivet hole  14   d  of the projecting portion  14   c . Formed at the radially outer end of the cap  20  is a stopper portion  20   b  that is bent at right angles, the stopper portion  20   b  engaging with an outer peripheral face of the radially outer end of the projecting portion  14   c  of the open flange part  14 . 
     The nozzle guide  22 , which is formed into an annular shape, includes a cylindrical portion  22   a  into which the fuel nozzle  15  is fitted and a bottom flange portion  22   c  that is bent from a corner portion  22   b  at one end of the cylindrical portion  22   a  at right angles and extends radially outward, and a plurality of cooling holes  22   d  are formed to extend through the corner portion  22   b . Two projecting portions  22   e  superimposed on the two projecting portions  14   c  of the open flange part  14  project from radially outer ends of the bottom flange portion  22   c  of the nozzle guide  22 , and U-shaped recess portions  22   f  opening radially outward are formed in the projecting portions  22   e.    
     The nozzle guide  22  of the present embodiment is a press-formed product, and the production cost is greatly reduced compared with a case in which it is formed from a machined product. 
     The cooling holes  22   d  of the nozzle guide  22  are inclined toward the axis L side in going from the outside to the inside of the combustor  11  when viewed in a direction orthogonal to the axis L (see  FIG. 2 ) and are inclined toward one side in the circumferential direction with respect to the axis L in going from the outside to the inside of the combustor  11  when viewed in the axis L direction (see  FIG. 3 ). The swirl direction of air supplied to the interior of the combustor  11  after passing through the cooling holes  22   d  of the nozzle guide  22  is set so as to be the same direction (clockwise direction in the present embodiment) as the swirl direction of air that is supplied to the interior of the combustor  11  after passing through the interior of the fuel nozzle  15 . 
     The projecting portion  22   e  of the nozzle guide  22  is sandwiched between the cap  20  and the projecting portion  14   c  of the open flange part  14 , and the recess portion  22   f  of the nozzle guide  22  is loosely fitted onto the outer periphery of the spacer  19 . In this state, the bottom flange portion  22   c  and the projecting portion  22   e  of the nozzle guide  22  have a gap α (see  FIG. 2 ) in the axis L direction between the cap  20  and the flat portion  14   b  and the projecting portion  14   c  of the open flange part  14 . The recess portion  22   f  of the nozzle guide  22  has a gap β (see  FIG. 2 ) in the radial direction and a gap γ (see  FIG. 3 ) in the circumferential direction between itself and the outer periphery of the spacer  19 . Therefore, the nozzle guide  22  can move in the axis L direction, the radial direction, and the circumferential direction relative to the open flange part  14 . 
     The operation of the embodiment of the present invention having the above arrangement is now explained. 
     During running of the gas turbine engine, air that has been compressed by a compressor is supplied to a space around the combustor  11  and is supplied therefrom to the interior of the combustor  11  after passing through the air inlet holes  12   b  of the combustor main body part  12  and the interior of the fuel nozzles  15 , and the air is mixed with fuel injected from the fuel nozzle  15  in the interior of the combustor  11 , thus carrying out combustion. Combustion gas generated by combustion is discharged from the combustor  11  and drives a turbine, and is then discharged via an exhaust nozzle and generates thrust. The spark plugs  18  ignite the mixed gas when the gas turbine engine is started, and combustion of the mixed gas continues automatically after starting the gas turbine engine. 
     Furthermore, air in the space around the combustor  11  passes through the cooling holes  22   d  of the nozzle guide  22  and is supplied to the interior of the combustor  11 , and in this process it cools the open flange part  14  and the fuel nozzle  15 . Air that has been supplied to the interior of the combustor  11  after passing through the cooling holes  22   d  is used for the combustion of fuel; since the cooling holes  22   d  are disposed so as to encircle the outer periphery of the fuel nozzle  15  and the swirl direction of air that is supplied to the interior of the combustor  11  after passing through the cooling holes  22   d  is set so as to be the same direction as the swirl direction of air that is supplied to the interior of the combustor  11  after passing through the interior of the fuel nozzle  15 , it is possible to form a strong swirl flow in the interior of the combustor  11  to thus stabilize the combustion of an air-fuel mixture. 
     Since the annular combustor  11  is cantilever-supported on the casing of the gas turbine engine via its inner peripheral part, and the base end parts of the fuel nozzles  15  and the spark plugs  18  are also cantilever-supported on the casing of the gas turbine engine, the fuel nozzles  15  and the spark plugs  18  move relative to the combustor  11  due to differences in the amount of thermal expansion accompanying change in temperature of the gas turbine engine. 
     However, since the nozzle guide  22  of the fuel nozzle  15  is supported on the open flange part  14  of the combustor  11  via the nozzle guide support means  16 , this nozzle guide support means  16  enables the nozzle guide  22  to move relative to the open flange part  14  in the axis L direction in a range of the gap α, in the radial direction in a range of the gap β, and in the circumferential direction in a range of the gap γ, these relative movements being allowed by the action of the gaps α, β, and γ. 
     Since assembly of the nozzle guide support means  16  is carried out by swaging the extremity of the rivet  21  extending through the rivet hole  20   a  of the cap  20 , the spacer  19 , and the rivet hole  14   d  of the projecting portion  14   c  of the open flange part  14  in the axis L direction, it becomes possible to cut the production time and the production cost compared with a case in which the nozzle guide support means  16  is assembled by welding or brazing. 
     Furthermore, since the nozzle guide support means  16 , which are divided into two parts, are disposed on the open flange part  14  at intervals of 180° in the circumferential direction, it is possible to cut the total weight of the nozzle guide support means  16  compared with a case in which one nozzle guide support means  16  is provided so as to follow the entire periphery of the open flange part  14 . 
     Moreover, since the nozzle guide support means  16  includes the cap  20  supporting the nozzle guide  22  in a floating state, the rivet  21  fixing the cap  20  to the open flange part  14 , and the spacer  19  fitted onto the outer periphery of the rivet  21  to thus form a projecting part for preventing rotation, not only is it possible to easily and reliably fix the cap  20  to the open flange part  14 , but it is also possible to restrict the gap in the axis L direction between the open flange part  14  and the cap  20  with good precision by utilizing the spacer  19  forming the projecting part. 
     Moreover, since the cap  20  includes the stopper portion  20   b , which can abut against the outer peripheral face of the projecting portion  14   c  of the open flange part  14 , it is possible by means of the stopper portion  20   b  to prevent the cap  20  from rotating around the rivet  21 . 
       FIG. 5A  shows a first comparative example of the present invention; a height H of an open flange part  14  projecting in the axis L direction is large, and cooling holes  22   d  of a nozzle guide  22  are formed in parallel to the axis L direction in a bottom flange portion  22   c . This first comparative example has the problem that the weight is large due to the height H of the open flange part  14  being large. 
       FIG. 5B  shows a second comparative example of the present invention; in order to lighten the weight a height H of an open flange part  14  is changed to be small. When the height H of the open flange part  14  is small, since the radial length of a flat portion  14   b  that abuts against a bottom flange portion  22   c  of a nozzle guide  22  increases, there is the problem that cooling holes  22   d  formed in the bottom flange portion  22   c  are blocked by the flat portion  14   b.    
       FIG. 5C  is the embodiment; the weight is lightened by making the height H of the open flange part  14  small as in the second comparative example, but since the cooling holes  22   d  are formed in the corner portion  22   b  and not in the bottom flange portion  22   c  of the nozzle guide  22 , and the cooling holes  22   d  are formed not in parallel to the axis L direction but radially inward toward the axis L, the cooling holes  22   d  will not be blocked by the flat portion  14   b  of the open flange part  14 . Moreover, since the bottom flange portion  22   c  of the nozzle guide  22  does not include the cooling holes  22   d , it is possible to reduce the radial dimension of the bottom flange portion  22   c  by an amount corresponding to the cooling holes  22   d , thus further lightening the weight. 
     An embodiment of the present invention is explained above, but the present invention may be modified in a variety of ways as long as the modifications do not depart from the gist thereof. 
     For example, the structure of the nozzle guide support means  16  supporting the nozzle guide  22  in a floating state is not limited to that of the embodiment.