Patent Application
20170299182
The present invention relates to a combustor in which a sound attenuator is provided on an outer circumferential side of a combustion liner in which a fuel is burned, and to a gas turbine including the combustor.
This application claims priority based on Japanese Patent Application No. 2014-195204 filed in Japan on Sep. 25, 2014, of which the contents are incorporated herein by reference.
A gas turbine includes a compressor that compresses air, a combustor that burns fuel in the air compressed by the compressor to generate a combustion gas, and a turbine that is driven by the combustion gas from the combustor.
As disclosed in Patent Document 1 indicated below, the combustor of the gas turbine includes, for example, a combustion liner (or transition piece) in which the fuel is burned, a fuel jetting device that jets the fuel and air into the combustion liner, a sound attenuator including an acoustic case provided on an outer circumferential side of the combustion liner, and a restrictor that reduces a flow path of a gas in the combustion liner. The restrictor is disposed in a position distanced from the sound attenuator in an axial direction of the combustion liner, and more specifically, in a position downstream from the sound attenuator.
The acoustic case includes part of a plate that forms the combustion liner, and an acoustic cover defining, in conjunction with this part of the plate, a space on the outer circumferential side of the combustion liner. A plurality of sound absorbing holes are defined in the part of the plate of the combustion liner that forms the acoustic case. The plurality of sound absorbing holes penetrate from within the combustion liner to a space within the acoustic case. Air vibrations produced when the fuel is burned in the combustion liner such as combustion oscillations, or noise, passes through the sound absorbing holes, spreads out within the acoustic case, and is quietened therein. Additionally, air within the acoustic case is discharged into the combustion liner through the sound absorbing holes defined in the combustion liner. Accordingly, high-temperature gas inside the combustion liner does not flow into the acoustic case.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-309644A
The air discharged into the combustion liner from the acoustic case cools the inner circumferential side of the combustion liner, and also cools combustible gases discharged into the combustion liner from a burner, such as fuel gases and premixed gas obtained by premixing fuel and air. When a combustible gas is cooled, the fuel contained in that combustible gas does not burn completely, which produces CO. Generally, from the standpoint of environmental protection, there is demand for a reduction in the amount of CO produced by the incomplete burning of fuel in combustors.
Accordingly, an object of the present invention is to provide a combustor that can reduce an amount of CO discharged, as well as a gas turbine including such a combustor.
According to an aspect of the invention for achieving the above-described object, a combustor includes a combustion liner, a sound attenuator, and a restrictor. The combustion liner has a tubular shape centered on an axis and is configured to allow a fuel to be burned on an inner circumferential side of the combustion liner. The sound attenuator includes part of a plate forming the combustion liner and an acoustic cover defining, in conjunction with the part of the plate, a space on an outer circumferential side of the combustion liner. The restrictor is configured to, in a part in an axial direction in which the axis extends, narrow and then widen a flow path of a gas flowing in the combustion liner, as the restrictor extends from an upstream side that is one side in the axial direction toward a downstream side that is another side in the axial direction. At least one through-hole penetrating to the space from within the combustion liner is defined in the part of the plate of the sound attenuator. The at least one through-hole includes a plurality of through-holes. A relative position in the axial direction of the restrictor with respect to the sound attenuator is a position such that at least some of the plurality of through-holes in the sound attenuator are present within a region spanning, in the axial direction, from a position of a minimum restrictor diameter of the restrictor to positions, on an upstream side and a downstream side, at a distance equivalent to a minimum restrictor radius that is half the minimum restrictor diameter.
Air within the space of the sound attenuator is discharged into the combustion liner through the through-holes in the sound attenuator. Accordingly, high-temperature gas inside the combustion liner does not flow into the space. The air discharged into the combustion liner from the space in the sound attenuator cools the fuel flowing within the combustion liner. There are thus cases where some of the fuel is not completely burned, which produces CO.
A vortex is formed in a region, within the combustion liner, downstream from the position of the minimum restrictor diameter and located toward the outer circumference of the combustion liner. In this vortex, the CO produced in a region along the inner circumferential surface of the combustion liner mixes with high-temperature combustion gas produced in a region distanced inward from the inner surface of the combustion liner in the radial direction. The CO produced in the region along the inner circumferential surface of the combustion liner is heated by the high-temperature combustion gas and burns as a result.
Basically, the gas within the combustion liner flows from the upstream side toward the downstream side. However, in reality, this flow is complex. Specifically, a plurality of vortices are formed in a complex manner within the combustion liner. An average diameter of the plurality of vortices is substantially equal to the minimum restrictor radius of the restrictor. According to this combustor, at least some of the through-holes in the sound attenuator are present in a region spanning from the position of the minimum restrictor diameter to positions, on the upstream side and the downstream side, at a distance equivalent to the minimum restrictor radius. Accordingly, even if the fuel present in the vortices within the combustion liner is cooled by the air discharged into the combustion liner from the sound attenuator and CO is produced as a result, much of the CO produced in the vortices can be burned due to the vortex formed on the downstream side of the restrictor present near the sound attenuator, before moving into other vortices and dispersing.
Thus according to this combustor, even if CO is produced by the air discharged from the sound attenuator into the combustion liner, that CO can be burned immediately.
Here, in the combustor according to the above-described aspect, the restrictor may be disposed downstream from the sound attenuator.
According to this combustor, even if CO is produced in a region along the inner circumferential surface of the combustion liner by the air discharged from the sound attenuator into the combustion liner, that CO can be burned due to the vortex formed downstream from the restrictor disposed on the downstream side of the sound attenuator.
In the combustor in which the restrictor is disposed downstream from the sound attenuator, the through-holes in the sound attenuator may be defined so as to shift downstream gradually as the through-holes extend from the outer circumferential side of the combustion liner toward the inner circumferential side of the combustion liner.
According to this combustor, air discharged from the sound attenuator into the combustion liner flows along the inner circumferential surface of the combustion liner, and then also flows along a surface of the restrictor. As such, according to this combustor, the restrictor can be cooled through film cooling by the air discharged from the sound attenuator, which makes it possible to suppress thermal damage to the restrictor.
In the combustor according to the above-described aspect, the restrictor may be disposed within a region, in the axial direction, in which the sound attenuator is present.
Some of the air in the sound attenuator is discharged directly to the upstream side of the minimum restrictor diameter of the restrictor, and the remaining air is discharged directly to the downstream side of the minimum restrictor diameter of the restrictor. Thus according to this combustor, before CO is produced by the air discharged into the combustion liner from the sound attenuator, that air can mix with high-temperature combustion gas within the vortex downstream from the restrictor. Additionally, according to this combustor, even if CO is produced by the air discharged into the combustion liner from the sound attenuator, that CO can be burned immediately due to the effect of the restrictor.
Additionally, in the combustor according to the above-described aspect, the restrictor may be disposed upstream from the sound attenuator.
All of the air from the sound attenuator is discharged downstream from the position of the minimum restrictor diameter of the restrictor, into the vortex formed on the downstream side of the minimum restrictor diameter. Thus according to this combustor, before CO is produced by the air discharged into the combustion liner from the sound attenuator, that air can mix with high-temperature combustion gas within the vortex downstream from the restrictor. Additionally, according to this combustor, even if CO is produced by the air discharged into the combustion liner from the sound attenuator, that CO can be burned immediately due to the effect of the restrictor.
In any of the combustors described above, the plurality of through-holes penetrating to the space from within the combustion liner may be defined in the part of the plate of the sound attenuator. A relative position in the axial direction of the restrictor with respect to the sound attenuator may be a position such that all of the through-holes in the sound attenuator are present within a region spanning, in the axial direction, from a position of the minimum restrictor diameter to positions, on an upstream side and a downstream side, at a distance equivalent to the minimum restrictor radius.
According to this combustor, the relative position of the restrictor, in the axial direction, is closer to the sound attenuator than that in the above-described combustors. As such, according to this combustor, even if CO is produced by the air discharged into the combustion liner from the sound attenuator, that CO can be burned more quickly.
Additionally, in any of the combustors described above, a plurality of the sound attenuators may be disposed at intervals in a circumferential direction based on the axis.
Additionally, in any of the combustors described above, a minimum restrictor portion that is a part of the restrictor having the minimum restrictor diameter, and a medium restrictor portion that is a part of the restrictor having a medium restrictor diameter greater than the minimum restrictor diameter, may be formed in the restrictor alternately in the circumferential direction.
In the combustor in which the minimum restrictor portion and the medium restrictor portion are formed in the restrictor, a plurality of the sound attenuators may be disposed at intervals in a circumferential direction based on the axis. Each of the plurality of sound attenuators may be disposed within a region through which virtual lines pass. The virtual lines extend in the axial direction from ends of a corresponding minimum restrictor portion of a plurality of minimum restrictor portions in the circumferential direction.
A vortex that is stronger than in other areas of the restrictor is formed on the downstream side of the end of the minimum restrictor portion in the circumferential direction. As such, when the end of the minimum restrictor portion in the circumferential direction is present within a region in which the corresponding sound attenuator is present, downstream from that region, or upstream from that region, even if CO is produced by the air discharged into the combustion liner from the sound attenuator, that CO can be efficiently burned on the downstream side of the end of the minimum restrictor portion in the circumferential direction.
In any of the combustors described above, at least one passage penetrating to the space from an exterior may be defined in the acoustic cover of the sound attenuator. Additionally, in the combustor described above, at least one passage may be defined in the combustion liner. An opening of the at least one passage is defined in a part of the outer circumferential surface of the combustion liner that is not covered by the acoustic cover. The at least one passage passes between the outer circumferential surface and the inner circumferential surface of the combustion liner. Another opening of the at least one passage is defined in a part of the outer circumferential surface of the combustion liner that is covered by the acoustic cover.
According to an aspect of the present invention for achieving the above-described object, a gas turbine includes any one of the above-described combustors, a compressor that compresses air and supplies the air to the combustor, and a turbine that is driven by combustion gas formed by a fuel being burned in the combustor.
According to an aspect of the present invention, an amount of CO discharged can be reduced.
An embodiment of a combustor and a gas turbine including the same, as well as various other embodiments and modified examples of the combustor, according to the present invention, will be described in detail hereinafter with reference to the drawings.
A first embodiment of a combustor and a gas turbine including the same according to the present invention will be described using
As illustrated in
The compressor 1 includes a compressor rotor 2 that rotates around a rotational axis Ar and a compressor casing 3 that covers the compressor rotor 2 while allowing the compressor rotor 2 to rotate. The turbine 5 includes a turbine rotor 6 that rotates around a rotational axis Ar and a turbine casing 7 that covers the turbine rotor 6 while allowing the turbine rotor 6 to rotate. The rotational axis Ar of the compressor rotor 2 and the rotational axis Ar of the turbine rotor 6 are located on the same straight line. The compressor rotor 2 and the turbine rotor 6 are connected with each other to form a gas turbine rotor 8. Meanwhile, the compressor casing 3 and the turbine casing 7 are connected with each other to form a gas turbine casing 9.
A generator rotor, for example, is connected to the gas turbine rotor 8. Furthermore, the combustors 4 are fixed to the gas turbine casing 9.
As illustrated in
As illustrated in
The pilot burner 11 is disposed on a combustor axis Ac. The plurality of main burners 12 are arranged in a circumferential direction, centered on the combustor axis Ac, while surrounding the outer circumferential side of the pilot burner 11. In the following, a direction in which the combustor axis Ac extends is referred to as an axial direction Da, one side in the axial direction Da is referred to as an upstream side, and the other side in the axial direction Da is referred to as a downstream side. Additionally, the circumferential direction centered on the combustor axis Ac is simply referred to as a circumferential direction Dc.
The combustion liner 20 includes a connecting portion 21 on an inner circumferential side of which downstream side portions of the plurality of main burners 12 are located, a combustion portion 22 forming a fuel region in which the fuel jetted from the main burners 12 and the pilot burner 11 is burned, and a combustion gas guide portion 23 that guides the combustion gas generated by the fuel being burned to the turbine 5. Both the connecting portion 21 and the combustion portion 22 form a cylindrical shape centered on the combustor axis Ac. The combustion gas guide portion 13 has a tubular shape. An upstream end of the connecting portion 21 of the combustion liner 20 is connected to the burner holding cylinder 15. The combustion portion 22 of the combustion liner 20 is formed on the downstream side of the connecting portion 21 of the combustion liner 20. The combustion gas guide portion 23 of the combustion liner 20 is formed on the downstream side of the combustion portion 22 of the combustion liner 20.
The combustor 4 further includes a sound attenuator 30 including an acoustic case 31 provided on an outer circumferential side of the combustion liner 20, and a restrictor 40 that reduces a flow path of gas within the combustion liner 20.
As illustrated in
The passages 35 serve as drain passages for discharging drainage that has accumulated in the acoustic case 31, as air introduction passages for introducing outside air into the acoustic case 31, and the like. Meanwhile, the through-holes 33 serve as sound absorbing holes for guiding air vibrations produced when the fuel is burned in the combustion liner 20 such as combustion oscillations, or noise, into the acoustic case 31, as air discharge holes for discharging air present in the acoustic case 31 into the combustion liner 20, and the like.
The restrictor 40 includes a connecting portion 41 connected to an inner circumferential surface of the combustion liner 20, and a diameter reducing portion 42 in which the inner diameter of the restrictor 40 gradually decreases as the restrictor 40 extends toward the downstream side. The connecting portion 41 forms a cylindrical shape centered on the combustor axis Ac. The diameter reducing portion 42 is formed integrally with the connecting portion 41. An inner diameter of a downstream end of the diameter reducing portion 42 corresponds to a minimum restrictor diameter 43, where the inner diameter of the diameter reducing portion 42 is the narrowest. The restrictor 40 gradually narrows a flow path of gas flowing within the combustion liner 20, and the flow path then suddenly becomes larger downstream from the minimum restrictor diameter 43. The sound attenuator 30 is provided upstream from the restrictor 40.
A relative position in the axial direction Da of the restrictor 40 with respect to the sound attenuator 30 is a position such that at least some of the through-holes 33 in the sound attenuator 30 are present within a region spanning, in the axial direction Da, from the position of the minimum restrictor diameter 43 to positions, on an upstream side and a downstream side, at a distance equivalent to a minimum restrictor radius R that is half the minimum restrictor diameter 43. Specifically, in the present embodiment, a distance L from the position of the minimum restrictor diameter 43 to the through-holes 33 that, of the plurality of through-holes 33 in the sound attenuator 30, are closest to the restrictor 40, is shorter than the minimum restrictor radius R. Furthermore, in the present embodiment, a distance from the position of the minimum restrictor diameter 43 to the through-holes 33 that, of the plurality of through-holes 33 in the sound attenuator 30, are farthest from the restrictor 40, is also shorter than the minimum restrictor radius R. As such, in the present embodiment, all of the through-holes 33 in the sound attenuator 30 are present in a region spanning from the position of the minimum restrictor diameter 43 to a position upstream therefrom at a distance equivalent to the minimum restrictor radius R.
Actions and effects of the gas turbine according to the present embodiment will be described next.
The compressor 1 sucks in and compresses outside air. The air compressed by the compressor 1 is guided into the main burners 12 and the pilot burner 11 of each combustor 4. Fuel is supplied to the main burners 12 and the pilot burner 11 from a fuel supply source. Each main burner 12 discharges premixed gas, obtained by premixing fuel and air, into the combustion portion 22 of the combustion liner 20. The premixed gas is burned through premixed combustion in the combustion portion 22. The pilot burner 11, meanwhile, jets fuel and air that have not been premixed into the combustion portion 22 of the combustion liner 20. This fuel is burned in the combustion portion 22 through diffusion combustion. High-temperature, high-pressure combustion gas generated by the fuel being burned in the combustion portion 22 of the combustion liner 20 is guided into a gas flow path of the turbine 5 by the combustion gas guide portion 23 of the combustion liner 20 to rotate the turbine rotor.
When the fuel is burned in the combustion liner 20, there are cases where the burning produces combustion oscillations. In the present embodiment, air vibrations produced when the fuel is burned in the combustion liner 20 such as combustion oscillations, or noise, is suppressed by the sound attenuator 30 provided on the outer circumferential side of the combustion liner 20. The acoustic case 31 of the sound attenuator 30 constitutes a Helmholtz resonance box. As such, noise produced by the fuel being burned in the combustion liner 20 passes through the through-holes 33, spreads out within the acoustic case 31, and is quieted therein.
Some of the air compressed by the compressor 1 flows into the acoustic case 31 from the exterior through the passages 35 in the acoustic case 31. The air within the acoustic case 31 is discharged into the combustion liner 20 through the through-holes 33 in the acoustic case 31. Accordingly, high-temperature gas inside the combustion liner 20 does not flow into the acoustic case 31.
The combustion liner 20 is cooled using steam generated at other locations, air compressed by the compressor 1, or the like as a cooling medium, for the purpose of protecting the combustion liner 20 from flames, high-temperature combustion gas, and the like. Thus, of the premixed gas discharged from the main burner 12, the premixed gas flowing in a region along the inner circumferential surface of the combustion liner 20 is cooled. Depending on the degree of cooling, the gas is not completely burned, which produces CO. In other words, depending on the operating state of the gas turbine, there are cases where CO is produced in the region along the inner circumferential surface of the combustion liner 20.
Accordingly, in the present embodiment, the restrictor 40 is provided in the combustion liner 20 in order to suppress the amount of CO discharged from the combustor 4. As described earlier, the restrictor 40 gradually narrows the flow path of gas flowing within the combustion liner 20, and then suddenly widens the flow path on the downstream side of the minimum restrictor diameter 43. Accordingly, a vortex S1 is formed in a region, within the combustion liner 20, downstream from the position of the minimum restrictor diameter 43 and located toward the outer circumference of the combustion liner 20. In this vortex S1, the CO produced in the region along the inner circumferential surface of the combustion liner 20 mixes with high-temperature combustion gas produced in a region distanced inward from the inner surface of the combustion liner 20 in the radial direction. The CO produced in the region along the inner circumferential surface of the combustion liner 20 is heated by the high-temperature combustion gas and burns as a result.
Thus, according to the present embodiment, even if CO is produced in the region along the inner circumferential surface of the combustion liner 20 when the operating state of the gas turbine is a predetermined operating state, ensuring that the CO is burned on the downstream side of the restrictor 40 makes it possible to suppress the amount of CO discharged from the combustor 4.
Incidentally, air is discharged into the combustion liner 20 from the acoustic case 31 through the through-holes 33. This air mixes with the premixed gas discharged from the main burner 12 and flows downstream in the combustion liner 20 along with the premixed gas. When the air from the acoustic case 31 mixes with the premixed gas, there are cases where the premixed gas is cooled, some of the premixed gas is not completely burned, and CO is produced as a result.
Basically, the gas within the combustion liner 20 flows from the upstream side toward the downstream side. However, in reality, this flow is complex. Specifically, a plurality of vortices S2 are formed in a complex manner within the combustion liner 20. An average diameter of the plurality of vortices S2 is substantially equal to the minimum restrictor radius R of the restrictor 40. Meanwhile, as described earlier, the distance L from the through-holes 33, of the plurality of through-holes 33 in the sound attenuator 30, that are located furthest downstream, to the position of the minimum restrictor diameter 43 of the restrictor 40, is shorter than the minimum restrictor radius R. Accordingly, even if the premixed gas present in the vortices S2 within the combustion liner 20 is cooled by the air discharged into the combustion liner 20 from the acoustic case 31 and CO is produced as a result, much of the CO produced in the vortices S2 can be burned due to the effect of the restrictor 40 present near the sound attenuator 30 before moving into other vortices S2 and dispersing.
Thus, according to the present embodiment, even if CO is produced by the air discharged into the combustion liner 20 from the acoustic case 31, that CO can be burned immediately, which makes it possible to suppress the amount of CO discharged from the combustor 4.
A second embodiment of a combustor will be described using
In the combustor according to the present embodiment, the relative positions of the sound attenuator 30 and the restrictor 40 are changed from those in the combustor according to the above-described first embodiment. Other configurations are the same as in the combustor according to the above-described first embodiment.
In the above-described first embodiment, the restrictor 40 is located downstream from the sound attenuator 30. However, in the present embodiment, the restrictor 40 is disposed in a region, in the axial direction Da, where the sound attenuator 30 is present. Therefore, in the present embodiment too, at least some of the through-holes 33 in the sound attenuator 30 are present in a region spanning, in the axial direction Da, from the position of the minimum restrictor diameter 43 to positions, on the upstream side and the downstream side, at a distance equivalent to the minimum restrictor radius R, in the same manner as in the above-described first embodiment.
In the present embodiment, some of the air in the acoustic case 31 is discharged directly to the upstream side of the minimum restrictor diameter 43 of the restrictor 40, and the remaining air is discharged directly to the downstream side of the minimum restrictor diameter 43 of the restrictor 40. Accordingly, in the present embodiment, before CO is produced by the air discharged into the combustion liner 20 from the acoustic case 31, that air can mix with the high-temperature combustion gas within the vortex S1 downstream from the restrictor 40. Additionally, in the present embodiment, even if CO is produced by the air discharged into the combustion liner 20 from the acoustic case 31, that CO can be burned immediately due to the effect of the restrictor 40.
A third embodiment of a combustor will be described using
Also in the combustor according to the present embodiment, the relative positions of the sound attenuator 30 and the restrictor 40 are changed from those in the combustor according to the above-described first embodiment. Other configurations are the same as in the combustor according to the above-described first embodiment.
In the above-described first embodiment, the restrictor 40 is located downstream from the sound attenuator 30. However, in the present embodiment, the restrictor 40 is disposed upstream from the sound attenuator 30. However, in the present embodiment, the distance L from the position of the minimum restrictor diameter 43 to the through-holes 33 that, of the plurality of through-holes 33 in the sound attenuator 30, are located closest to the restrictor 40, is shorter than the minimum restrictor radius R. Furthermore, in the present embodiment, the distance from the position of the minimum restrictor diameter 43 to the through-holes 33 that, of the plurality of through-holes 33 in the sound attenuator 30, are located farthest from the restrictor 40, is also smaller than the minimum restrictor radius R. As such, in the present embodiment, all of the through-holes 33 in the sound attenuator 30 are present in a region spanning from the position of the minimum restrictor diameter 43 to a position downstream therefrom at a distance equivalent to the minimum restrictor radius R.
All of the air from the acoustic case 31 is discharged downstream from the position of the minimum restrictor diameter 43 of the restrictor 40, into the vortex S1 formed on the downstream side of the minimum restrictor diameter 43. Accordingly, in the present embodiment too, before CO is produced by the air discharged into the combustion liner 20 from the acoustic case 31, that air can mix with the high-temperature combustion gas within the vortex S1 downstream from the restrictor 40, in the same manner as in the second embodiment. Furthermore, in the present embodiment, even if CO is produced by the air discharged into the combustion liner 20 from the acoustic case 31, that CO can be burned immediately due to the effect of the restrictor 40, in the same manner as in the second embodiment.
A fourth embodiment of a combustor will be described using
The combustor according to the present embodiment is obtained by changing the sound attenuator 30 and the restrictor 40 of the combustor according to the above-described first embodiment.
The sound attenuator 30 according to the above-described first embodiment includes the single acoustic cover 34 covering a region that corresponds to part of the combustion liner 20 in the axial direction Da and spans the entire combustion liner 20 in the circumferential direction Dc. In other words, in the combustor according to the above-described first embodiment, the single sound attenuator 30 is provided in a region corresponding to part of the combustion liner 20 in the axial direction Da. However, in the combustor according to the present embodiment, a plurality of sound attenuators 30a arranged at intervals in the circumferential direction Dc are provided in a region corresponding to part of the combustion liner 20 in the axial direction Da, as illustrated in
Like the sound attenuator 30 according to the above-described first embodiment, each sound attenuator 30a according to the present embodiment includes a liner-side case formation plate portion 32a that is part of the plate forming the combustion liner 20, and an acoustic cover 34a that, in conjunction with the liner-side case formation plate portion 32a, defines a resonance space 36a on the outer circumferential side of the combustion liner 20. The acoustic cover 34a covers a region, of the plate that forms the combustion liner 20, corresponding to part of the combustion liner 20 in the axial direction Da and part of the combustion liner 20 in the circumferential direction Dc. As such, the liner-side case formation plate portion 32a according to the present embodiment is a portion that forms a region, of the plate that forms the combustion liner 20, corresponding to part of the combustion liner 20 in the axial direction Da and part of the combustion liner 20 in the circumferential direction Dc.
Like the restrictor 40 according to the above-described first embodiment, a restrictor 40a according to the present embodiment includes the connecting portion 41 connected to the inner circumferential surface of the combustion liner 20 and a diameter reducing portion 42a formed integrally with the connecting portion 41. In the diameter reducing portion 42a, the inner diameter of the restrictor 40a gradually decreases as the restrictor 40a extends toward the downstream side. In the present embodiment too, an inner diameter of a downstream end of the diameter reducing portion 42a corresponds to the minimum restrictor diameter 43, where the inner diameter of the diameter reducing portion 42a is the narrowest. However, in the diameter reducing portion 42a of the restrictor 40a in the present embodiment, a plurality of cuts are defined and arranged in the circumferential direction Dc. The plurality of cuts are cut outward in the radial direction and upstream from the position of the minimum restrictor diameter 43. The plurality of cuts form minimum restrictor portions 44 and medium restrictor portions 45 in the diameter reducing portion 42a, alternately in the circumferential direction Dc. The minimum restrictor portions 44 are parts corresponding to the minimum restrictor diameter 43. The medium restrictor portions 45 are at a greater diameter than the minimum restrictor diameter 43. A side 44x that forms the minimum restrictor diameter 43 and a side 44y where the minimum restrictor portion 44 transitions to the medium restrictor portion 45 form a corner at each position of an end 44z of the minimum restrictor portion 44 in the circumferential direction Dc.
In the present embodiment, the number of the plurality of sound attenuators 30a arranged in the circumferential direction Dc, the number of the minimum restrictor portions 44 in the restrictor 40a, and the number of the medium restrictor portions 45 in the restrictor 40a are the same. Additionally, each sound attenuator 30a is disposed within a region W through which virtual lines Lv pass. The virtual lines Lv extend in the axial direction Da from the ends 44z of the minimum restrictor portions 44 in the circumferential direction Dc. To rephrase, the entire minimum restrictor portion 44 in the circumferential direction Dc is present on the downstream side of the corresponding sound attenuator 30a.
A vortex S1a that is stronger than in other parts of the restrictor 40a is formed on the downstream side of the end 44z of the minimum restrictor portion 44 in the circumferential direction Dc, or in other words, on the downstream side of the corner of the restrictor 40a. As such, when a corner of the restrictor 40a is present on the downstream side of each sound attenuator 30a, even if the premixed gas is cooled by air discharged into the combustion liner 20 from acoustic cases 31a and CO is produced as a result, that CO can be efficiently burned on the downstream sides of the corners of the restrictor 40a.
Accordingly, as long as at least one corner of the restrictor 40a is present on the downstream side of each sound attenuator 30a, even if CO is produced by the air discharged into the combustion liner 20 from the acoustic cases 31a, that CO can be efficiently burned. Thus as illustrated in
Although the present embodiment describes an example in which the restrictor 40 is disposed on the downstream side of the sound attenuators 30a, employing the restrictor 40a according to the present embodiment makes it possible to achieve the same effects even in a case where the restrictor is disposed in a region in the axial direction Da where the sound attenuator is present, as in the second embodiment, a case where the restrictor is disposed upstream from the sound attenuator, as in the third embodiment, and the like.
A first modified example of the combustor will be described using
In the combustor according to the modified example, the direction in which the through-holes 33 penetrate is different from that in the combustor according to the above-described first embodiment. Other configurations are the same as in the combustor according to the above-described first embodiment.
Through-holes 33a according to the present modified example penetrate the liner-side case formation plate portion 32 and shift from upstream to downstream gradually as the through-holes extend from the outside in the radial direction toward the inside in the radial direction. As such, air discharged from the acoustic case 31 into the combustion liner 20 through the through-holes 33a flows along the inner circumferential surface of the combustion liner 20, and then also flows along a surface of the restrictor 40. As such, according to the present modified example, the restrictor 40 can be cooled through film cooling by the air discharged from the acoustic case 31, which makes it possible to suppress thermal damage to the restrictor 40. The air flowing along the surface of the restrictor 40 mixes with the high-temperature combustion gas in the vortex S1 formed on the downstream side of the restrictor 40, in the same manner as in the above-described first embodiment.
A second modified example of the combustor will be described using
In the combustor according to the present modified example, the shape of the restrictor 40 is different from that in the combustor according to the above-described first embodiment. Other configurations are the same as in the combustor according to the above-described first embodiment.
With the restrictor 40 according to the above-described first embodiment, the vortex S1 is formed on the downstream side of the minimum restrictor diameter 43, and thus there are no parts of the restrictor 40 present downstream from the minimum restrictor diameter 43. However, as long as the vortex S1 can be formed on the downstream side of the minimum restrictor diameter 43, part of the restrictor may be present downstream from the minimum restrictor diameter 43. Specifically, the restrictor may include, downstream from the minimum restrictor diameter 43, a diameter expanding portion of which the inner diameter gradually increases as the diameter expanding portion extends downstream. For example, this restrictor 40b includes an upstream-side connecting portion 41, the diameter reducing portion 42, a diameter expanding portion 46, and a downstream-side connecting portion 47. The upstream-side connecting portion 41 is connected to the inner circumferential surface of the combustion liner 20. The diameter reducing portion 42 is formed integrally with the upstream-side connecting portion 41. The inner diameter of the diameter reducing portion 42 gradually decreases as the diameter reducing portion 42 extends downstream. The diameter expanding portion 46 is connected to a downstream end of the diameter reducing portion 42. The inner diameter of the diameter expanding portion 46 gradually increases as the diameter expanding portion 46 extends downstream. The downstream-side connecting portion 47 is connected to a downstream end of the diameter expanding portion 46 and the inner circumferential surface of the combustion liner 20.
The minimum restrictor diameter 43 corresponds to the position of the downstream end of the diameter reducing portion 42, or in other words, the position of an upstream end of the diameter expanding portion 46. Preferably, an angle α of a surface of the diameter expanding portion 46 relative to a surface of the diameter reducing portion 42 is no greater than 1450, for example, to ensure that the flow of the vortex S1 is formed on the downstream side of the minimum restrictor diameter 43. Here, to connect the restrictor 40b to the inner circumferential surface of the combustion liner 20, the restrictor 40b according to the present modified example includes the upstream-side connecting portion 41 and the downstream-side connecting portion 47. However, one of the upstream-side connecting portion 41 and the downstream-side connecting portion 47 may be omitted.
A third modified example of the combustor will be described using
In the combustor according to the present modified example, the positions of the passages 35 that allow the interior of the resonance space 36 to communicate with the exterior are different from those in the combustor according to the above-described first embodiment. Other configurations are the same as in the combustor according to the above-described first embodiment.
In the above-described first embodiment, the passages 35 that allow the interior of the resonance space 36 to communicate with the exterior are provided in the acoustic cover 34. However, as long as the passages enable air to be supplied to the interior of the resonance space 36 from the exterior, the passages are not limited to the passages 35. For example, as illustrated in
According to an aspect of the present invention, an amount of CO discharged can be reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-195204 | Sep 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/074930 | 9/2/2015 | WO | 00 |
