JP2017227147A - Turbine, gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine having improved performance.SOLUTION: A turbine 2 comprises: a turbine rotor 91 rotatable toward one circumferential direction of an axis Am; a turbine casing 92; a plurality of turbine buckets 24 aligned in the circumferential direction of the axis Am on the outer peripheral surface of the turbine rotor 91 and at least the part of on the other side in the axial Am direction being curved from one circumferential direction toward the other side; a plurality of turbine stationary blades 26 aligned in the circumferential direction; and a diffuser 4 that defines an exhaust air stream C through which exhaust gas circulates from one side in the axial Am direction toward the other side. The diffuser 4 includes: an inner cylinder 41; an external cylinder 42 that defines the exhaust air stream C between itself and the inner cylinder 41; and a plurality of struts 43 formed with a first surface S1 facing one side in the circumferential direction. The first surface S1 includes a first inclined plane T1 extending from the one side in the circumferential direction to the other side as going radially outward from the outer peripheral surface 41A of the inner cylinder 41.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a turbine and a gas turbine.

A typical gas turbine includes a compressor, a combustor, and a turbine. The compressor generates high-pressure air by compressing outside air. The combustor generates high-temperature and high-pressure combustion gas by mixing fuel with high-pressure air and burning it. The turbine is driven by combustion gas.
In general, a diffuser is provided on the downstream side of the turbine (see Patent Document 1 below). More specifically, the diffuser connects an inner cylinder provided on the inner peripheral side, an outer cylinder that defines an exhaust passage by covering the inner cylinder from the outer peripheral side, and the inner cylinder and the outer cylinder. And a plurality of struts extending in the radial direction of the turbine. The exhaust passage gradually increases in diameter from the upstream side to the downstream side in the direction in which the combustion gas flows. As a result, the combustion gas (exhaust gas) that has driven the turbine passes through the diffuser and the static pressure is increased, and is discharged to the outside.

Japanese Patent No. 5693315

  Here, the flow of the combustion gas discharged from the turbine includes an axial component and a swirl component (swirl component) that swirls in the circumferential direction with respect to the axial direction. On the other hand, the struts described above extend in the radial direction of the turbine. For this reason, when the flow of the exhaust gas passes around the strut, the strut causes a shape resistance or a separation of the flow. This may cause a pressure loss in the exhaust gas flow.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a turbine and a gas turbine having improved performance.

  A turbine according to a first aspect of the present invention includes a turbine rotor that extends along an axis and is rotatable toward one side in a circumferential direction of the axis, a turbine casing that covers the turbine rotor from an outer peripheral side, and the turbine A plurality of turbine rotor blades arranged on the outer circumferential surface of the rotor in the circumferential direction of the axis, wherein at least a portion on the other side in the axial direction is curved from one side in the circumferential direction to the other side; A plurality of turbine stationary blades arranged in the circumferential direction and adjacent to the turbine rotor blade on the circumferential surface, and provided on the other axial side of the turbine rotor blade, the axial direction A diffuser defining an exhaust passage through which exhaust gas flows from one side to the other side, and the diffuser includes an inner cylinder extending along the axis; The inner cylinder is covered from the outer peripheral side, and is provided with an outer cylinder that defines the exhaust passage between the inner cylinder and the inner cylinder, and a circumferential interval is provided in the exhaust passage. A plurality of struts connected to the outer cylinder and formed with a first surface facing one side in the circumferential direction, the first surface going radially outward from the outer circumferential surface of the inner cylinder It has the 1st inclined surface extended from the circumferential direction one side to the other side.

Here, the fluid that has passed through the turbine rotor blade often forms a swirl flow as a result of the flow pattern design of the turbine rotor blade and the turbine stationary blade. Further, when the axial flow velocity is relatively small as in the partial load, the swirl flow becomes larger than that at the rated load. When the swirl flow becomes large in this way, the exhaust gas is easily separated from the inner cylinder.
In general, when a structure is present in the fluid flow, the vorticity generated by the boundary layer is wound around both sides of the structure to generate a horseshoe vortex having a spiral vortex structure. In the present embodiment, since the first inclined surface extends from the one circumferential side to the other side in the radial direction from the outer circumferential surface of the inner cylinder, the region on the one circumferential side of the first inclined surface. Then, a horseshoe vortex containing a component extending in the axial direction develops outstandingly. By developing the horseshoe vortex in this way, in the region on one side in the circumferential direction of the first inclined surface, the fluid (exhaust gas) in the low momentum region near the first inclined surface that is a solid wall surface Since the momentum is added, the flow of the exhaust gas is positively attached to the inner cylinder side (radially inside). Thereby, it can suppress that the flow of exhaust gas peels from an inner cylinder.
In addition, since the first inclined surface is formed on the strut, a pressure gradient from the outer peripheral side toward the inner cylinder is formed in the vicinity of the inner cylinder. Specifically, the pressure in the region on one side in the circumferential direction of the first inclined surface is higher than the pressure in the region on the other side in the circumferential direction. Thereby, the flow which goes to the other side from the circumferential direction one side arises on the circumferential direction one side of the strut. As a result, pressure can be supplied to the other circumferential side of the strut. Therefore, it can suppress that the flow of exhaust gas peels from the inner cylinder also on the other circumferential side of the strut.
As described above, even when the swirl flow is large, it is possible to suppress the pressure loss in the exhaust flow path caused by the separation of the flow from the outer peripheral surface of the inner cylinder.

  In the turbine according to the second aspect of the present invention, the first surface is provided on the radially outer side of the first inclined surface, and is directed from the other side in the circumferential direction toward the one side in the radial direction from the inner side to the outer side. It may have a first outer inclined surface extending in the direction.

According to this configuration, a horseshoe vortex including a component extending in the axial direction is formed in a region on one circumferential side of the first outer inclined surface. By the formation of this horseshoe vortex, momentum is added to the flow of exhaust gas in the low momentum region near the first inclined surface, which is a solid wall surface, in the region on one side in the circumferential direction of the first outer inclined surface. Therefore, the flow of the exhaust gas is positively attached to the outer cylinder side (radially outer side). That is, it is possible to reduce the possibility of the exhaust gas flow separating from the outer cylinder on one side in the circumferential direction of the first outer inclined surface.
In addition, since the first inclined surface is formed on the strut, a pressure gradient from the outer peripheral side toward the inner cylinder is formed in the vicinity of the inner cylinder. Specifically, the pressure in the region on the one side in the circumferential direction of the first outer inclined surface is higher than the pressure in the region on the other side in the circumferential direction. That is, a pressure gradient is formed in which the pressure decreases from one circumferential side of the strut toward the other side. Due to this pressure gradient, the flow of the exhaust gas flows so as to be pressed toward the outer peripheral surface of the inner cylinder. As a result, pressure can be supplied to the other circumferential side of the strut, and the possibility of the exhaust gas flow separating from the outer cylinder on the other circumferential side of the strut can be reduced. Thereby, the pressure loss in an exhaust flow path by a flow peeling from the internal peripheral surface of an outer cylinder can be suppressed.

  In the turbine according to the third aspect of the present invention, the strut is formed with a second surface facing the other circumferential side, and the second surface is directed radially outward from the outer circumferential surface of the inner cylinder. You may have the 2nd inclined surface extended from the circumferential direction one side to the other side.

  In this configuration, of the swirling flow swirling toward one side in the circumferential direction, the component flowing in the relatively radially inner region flows from the radially outer side toward the inner side along the second inclined surface. Thereby, a flow can be made to adhere actively with respect to the outer peripheral surface of an inner cylinder. That is, flow separation on the outer peripheral surface of the inner cylinder can be further suppressed.

  In the turbine according to the fourth aspect of the present invention, the second surface is provided on the radially outer side of the second inclined surface, and moves from the other side in the circumferential direction toward the one side as it goes from the radially inner side to the outer side. It may have a 2nd outside inclined surface extended.

  In this configuration, of the swirling flow swirling toward the one side in the circumferential direction, the component flowing in the relatively radially outer region flows from the radially inner side toward the outer side along the second outer inclined surface. Thereby, a flow can be positively attached to the inner peripheral surface of the outer cylinder. That is, the separation of the flow on the inner peripheral surface of the outer cylinder can be further suppressed.

  In the turbine according to the fifth aspect of the present invention, the second inclined surface may extend from the outer peripheral surface of the inner cylinder to the inner peripheral surface of the outer cylinder.

  According to this configuration, the first inclined surface extends from the outer peripheral surface of the inner cylinder to the inner peripheral surface of the outer cylinder. In other words, the first inclined surface continuously extends without being bent from the outer peripheral surface of the inner cylinder to the inner peripheral surface of the outer cylinder. Thereby, compared with the structure by which the bending part is formed in the 1st inclined surface, the rigidity of a strut can be improved, for example.

  A gas turbine according to a sixth aspect of the present invention includes a compressor that generates high-pressure air, a combustor that generates high-temperature and high-pressure combustion gas by mixing fuel in the high-pressure air and burning it, and the combustion gas And the turbine according to any one of the above aspects driven by the motor.

  According to this structure, the gas turbine which can be efficiently operated can be obtained by suppressing the pressure loss in the turbine.

  According to the present invention, a turbine with improved performance and a gas turbine can be provided.

It is a figure showing composition of a gas turbine concerning a first embodiment of the present invention. It is sectional drawing which shows the structure of the diffuser which concerns on 1st embodiment of this invention, Comprising: It is a figure which shows the cross section containing an axis line. It is sectional drawing which shows the structure of the diffuser which concerns on 1st embodiment of this invention, Comprising: It is a figure which shows the cross section seen from the axial direction. It is a graph which shows an example of the turning angle distribution of the exhaust gas which distribute | circulates the inside of the diffuser (around strut) which concerns on 1st embodiment of this invention. It is a principal part enlarged view of the strut which concerns on 1st embodiment of this invention, Comprising: It is a figure which shows typically the flow of the exhaust gas which distribute | circulates the circumference | surroundings of a strut. It is a figure which shows the comparative example with respect to the strut which concerns on 1st embodiment of this invention. It is sectional drawing which shows the structure of the diffuser which concerns on 2nd embodiment of this invention, Comprising: It is a figure which shows the cross section seen from the axial direction. It is sectional drawing which shows the structure of the diffuser which concerns on 3rd embodiment of this invention, Comprising: It is a figure which shows the cross section seen from the axial direction.

[First embodiment]
A first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a gas turbine 100 according to this embodiment includes a compressor 1 that generates high-pressure air, a combustor 3 that generates combustion gas by mixing fuel with high-pressure air, and combustion. And a turbine 2 driven by gas.

  The compressor 1 includes a compressor rotor 11 that extends along the axis Am, and a compressor casing 12 that covers the compressor rotor 11 from the outer peripheral side. A plurality of compressor blade stages 13 arranged at intervals in the axis Am direction are provided on the outer peripheral surface of the compressor rotor 11. Each compressor blade stage 13 has a plurality of compressor blades 14 arranged on the outer peripheral surface of the compressor rotor 11 at intervals in the circumferential direction of the axis Am. A plurality of compressor vane stages 15 arranged at intervals in the axis Am direction are provided on the inner peripheral surface of the compressor casing 12. The compressor vane stages 15 are alternately arranged in the direction of the axis Am with respect to the compressor rotor stage 13 described above. Each compressor stationary blade stage 15 has a plurality of compressor stationary blades 16 arranged on the inner peripheral surface of the compressor casing 12 at intervals in the circumferential direction of the axis Am.

  The combustor 3 is provided between the compressor casing 12 and a turbine casing 22 (described later). High-pressure air generated by the compressor 1 is guided to the combustor 3. A fuel is mixed with this high-pressure air and burned to generate high-temperature and high-pressure combustion gas. The combustion gas flows into the turbine 2 and drives it.

  The turbine 2 includes a turbine rotor 21 that extends along the axis Am, a turbine casing 22 that covers the turbine rotor 21 from the outer peripheral side, and a diffuser 4. A plurality of turbine rotor blade stages 23 arranged at intervals in the axis Am direction are provided on the outer peripheral surface of the turbine rotor 21. Each turbine blade stage 23 has a plurality of turbine blades 24 arranged on the outer peripheral surface of the turbine rotor 21 at intervals in the circumferential direction of the axis Am. A plurality of turbine vane stages 25 arranged at intervals in the axis Am direction are provided on the inner peripheral surface of the turbine casing 22. The turbine stationary blade stages 25 are alternately arranged in the axis Am direction with respect to the turbine rotor blade stages 23. Each turbine stationary blade stage 25 has a plurality of turbine stationary blades 26 arranged on the inner peripheral surface of the turbine casing 22 at intervals in the circumferential direction of the axis Am.

  The compressor rotor 11 and the turbine rotor 21 are integrally connected in the axis Am direction, thereby forming a gas turbine rotor 91. Similarly, the compressor casing 12 and the turbine casing 22 are integrally connected along the axis Am to form a gas turbine casing 92. The gas turbine rotor 91 is integrally rotatable around the axis Am within the gas turbine casing 92.

  The diffuser 4 is provided integrally with the turbine casing 22 (gas turbine casing 92). More specifically, the diffuser 4 includes an inner cylinder 41 extending along the axis Am, an outer cylinder 42 that covers the inner cylinder 41 from the outer peripheral side, and a plurality of first cylinders that connect the inner cylinder 41 and the outer cylinder 42. A strut 43 (strut) and a second strut 44. A space surrounded by the outer peripheral surface 41A of the inner cylinder 41, the inner peripheral surface 42A of the outer cylinder 42, and a pair of first struts 43 adjacent in the circumferential direction is an exhaust passage C through which exhaust gas discharged from the turbine 2 flows. It is said that.

  Next, the detailed configuration of the diffuser 4 will be described with reference to FIG. The inner cylinder 41 of the diffuser 4 extends along the axis Am, and a bearing device (not shown) that rotatably supports the shaft end portion 91A of the gas turbine rotor 91 is provided inside thereof. The outer peripheral surface of the inner cylinder 41 is gradually reduced in diameter as it goes from one side to the other side in the axis Am direction.

  The outer cylinder 42 has a cylindrical shape that covers the inner cylinder 41 from the outer peripheral side. The inner peripheral surface 42A of the outer cylinder 42 is gradually enlarged in diameter from one side to the other side in the axis Am direction. That is, the space (exhaust flow path C) defined between the outer cylinder 42 and the inner cylinder 41 is its cross-sectional area (when viewed from the axis Am direction) as it goes from one side to the other side in the axis Am direction. The cross-sectional area is gradually expanding. Thereby, the kinetic energy of the fluid (exhaust gas) flowing through the exhaust passage C is converted into pressure.

  The first strut 43 and the second strut 44 are provided between the inner cylinder 41 and the outer cylinder 42. The first struts 43 and the second struts 44 are provided mainly for fixing and supporting the outer cylinder 42 with respect to the inner cylinder 41. The first strut 43 faces the final stage located on the most other side in the axis Am direction among the plurality of turbine rotor blade stages 23. As shown in FIG. 3, in the present embodiment, six first struts 43 are provided that extend radially from the inner cylinder 41 toward the outer peripheral side. These six first struts 43 are arranged at equal intervals in the circumferential direction of the axis Am.

  Each first strut 43 takes a form (tangential strut) inclined with respect to the tangential direction of the outer peripheral surface 41 </ b> A of the inner cylinder 41. More specifically, the first strut 43 extends from the other side in the circumferential direction of the axis Am toward one side as it goes from the radially inner side to the outer side of the axis Am. A surface of the first strut 43 facing the one side in the circumferential direction is a first surface S1. On the other hand, the surface facing the other circumferential side of the first strut 43 is a second surface S2. In the present embodiment, the first surface S1 and the second surface S2 both extend in the same direction from the radially inner side (the outer peripheral surface of the inner tube 41 to the outer side (the inner peripheral surface of the outer tube 42). Specifically, the first surface S1 has a first inclined surface T1 extending from one side in the circumferential direction toward the other side from the inner side toward the outer side in the radial direction. A second inclined surface T2 extending from one side in the circumferential direction toward the other side from the inner side to the outer side is provided, and the radially inner ends of the first inclined surface T1 and the second inclined surface T2 are respectively provided. It is connected to the outer peripheral surface 41 </ b> A of the inner cylinder 41, and the radially outer end is connected to the inner peripheral surface 42 </ b> A of the outer cylinder 42.

  The second strut 44 is a member provided to support the load of the outer cylinder 42 with respect to the inner cylinder 41, and is provided mainly for distributing the load burden of the first strut 43. The second strut 44 is provided at a position spaced from the first strut 43 on the other side in the axis Am direction. In the present embodiment, two second struts 44 extending in a direction away from the outer peripheral surface 41A of the inner cylinder 41 are provided. Each second strut 44 extends parallel to the radial direction of the axis Am.

  In operating the gas turbine 100 configured as described above, the compressor rotor 11 (gas turbine rotor 91) is first rotationally driven by an external drive source. As the compressor rotor 11 rotates, external air is sequentially compressed to generate high-pressure air. This high-pressure air is supplied into the combustor 3 through the compressor casing 12. In the combustor 3, the fuel is mixed with the high-pressure air and burned to generate high-temperature and high-pressure combustion gas. Combustion gas is supplied into the turbine 2 through the turbine casing 22. In the turbine 2, the combustion gas sequentially collides with the turbine rotor blade stage 23 and the turbine stationary blade stage 25, whereby a rotational driving force is given to the turbine rotor 21 (gas turbine rotor 91). This rotational energy is used to drive the generator GG connected to the shaft end. The combustion gas that has driven the turbine 2 is discharged to the outside after the pressure (static pressure) is increased as it passes through the exhaust passage C of the diffuser 4 as exhaust gas.

  Next, the behavior of the exhaust gas in the diffuser 4 will be described with reference to FIGS. As described above, in the turbine 2 according to the present embodiment, the trailing edge side (the portion on the other side in the axis Am direction) of the turbine blade 24 at the final stage is curved from one side in the circumferential direction to the other side, and The turbine rotor 21 rotates from the other side in the circumferential direction toward one side. At this time, the exhaust gas flowing into the diffuser 4 is given a swirl flow component swirling in the circumferential direction of the axis Am. (The arrow A in FIG. 3 represents the swirling direction of this swirling flow.) In particular, when the gas turbine 100 is rated, the swirling angle of the swirling flow around the first strut 43 is as shown in FIG. It is known to show a distribution as indicated by a chain line in the graph.

  In the graph of FIG. 4, the horizontal axis represents the turning angle of the swirling flow. The plus (+) side of the horizontal axis indicates a state in which the swirling flow is flowing from the other side in the circumferential direction toward one side, and the minus (−) side is the direction in which the swirling flow is from one side in the circumferential direction toward the other side. It shows the flowing state. The vertical axis represents radial position coordinates on the first strut 43 with the end on the radially inner side (inner cylinder 41 side) of the first strut 43 as the origin.

  In general, the gas turbine 100 is designed so that the swirl flow becomes as small as possible in order to reduce pressure loss due to interference between the flow and the flow passage structure during rated operation. In the present embodiment, as indicated by a chain line in the figure as an example, during the rated operation of the gas turbine 100, the region including the end portion on the inner cylinder 41 side of the first strut 43 and the end portion on the outer cylinder 42 side are defined. In the containing region, a swirling flow in the negative direction is generated. On the other hand, in a region surrounded by these two regions, a positive swirl flow is generated.

  On the other hand, when the gas turbine 100 is operated at a partial load, the swirl flow becomes large. As a result, the influence of separation of the flow from the structure in the flow path tends to increase. Along with this, the pressure loss increases. In the present embodiment, as an example, the swirling flow around the first strut 43 shows a distribution as shown by a solid line in FIG. That is, a swirling flow in the negative direction is generated over the entire extension region of the first strut 43.

Here, as described above, the first surface S1 of the first strut 43 has the first inclined surface T1 extending from the one side in the circumferential direction toward the other side from the inner side in the radial direction. That is, this 1st inclined surface T1 is extended so that it may incline in the direction opposite to said turning component as it goes to an outer side from radial inside. Thereby, in the area | region of the circumferential direction one side of 1st inclined surface T1, the vortex V1 as a horseshoe vortex containing the component extended to an axis line Am direction develops outstandingly. The horseshoe vortex is a vortex having a spiral tubular structure that is generated when a vorticity generated by a boundary layer is wound around both sides of a structure when the structure exists in the flow.
The vortex V1 forms a horseshoe-shaped vortex tube that extends so as to surround the first strut 43 from the other side in the axis Am direction when viewed from the outside in the radial direction. The vortex V1 flows along the first inclined surface T1 toward the outer peripheral surface 41A of the inner cylinder 41, and then flows again toward the first inclined surface T1 while being separated from the outer peripheral surface 41A. That is, when viewed from one side in the axis Am direction, the vortex V1 rotates counterclockwise. Since such a vortex V1 is formed, momentum is added to the boundary layer formed in the vicinity of the first inclined surface T1 in the region on one circumferential side of the first inclined surface T1. The exhaust gas flow is positively attached to the outer peripheral surface 41A of the inner cylinder 41. That is, it is possible to reduce the possibility of the exhaust gas flow separating from the inner cylinder 41 on one side in the circumferential direction of the first inclined surface T1.

  In addition, since the vortex V1 is formed, the pressure in the region on one side in the circumferential direction of the first inclined surface T1 becomes higher than the pressure in the region on the other side in the circumferential direction of the second inclined surface T2. As a result, a pressure gradient is formed on one side in the circumferential direction of the first strut 43 so that the pressure decreases from one side in the circumferential direction toward the other side. Due to this pressure gradient, the exhaust gas flows so as to be pressed toward the outer peripheral surface 41 </ b> A of the inner cylinder 41. As a result, pressure can be supplied to the other circumferential side of the second inclined surface T2. Therefore, it is possible to reduce the possibility that the exhaust gas flow is separated from the outer peripheral surface 41 </ b> A of the inner cylinder 41 on the other circumferential side of the second inclined surface T <b> 2. Thereby, the pressure loss in the exhaust flow path C can be suppressed.

  On the other hand, for example, as shown in FIG. 6, when the first strut 43 is inclined in the direction opposite to the above (ie, as it goes from the radially inner side to the outer side, it is inclined from the other circumferential side to the one side). In the vicinity of the outer peripheral surface 41A of the inner cylinder 41, a pressure gradient from the radially inner side to the outer side is formed. Thereby, there exists a possibility that the stability of the boundary layer formed in the vicinity of the said outer peripheral surface 41A may be impaired. However, in the turbine 2 according to the present embodiment and the gas turbine 100 including the turbine 2, it is possible to suppress pressure loss around the first strut 43 at the time of partial load as described above.

  In particular, in determining the shape and posture of a tangential strut such as the first strut 43, it has been common to assume only the behavior of exhaust gas during rated operation. That is, as an example, when the swirling flow swirls from the other side in the circumferential direction as viewed from one side in the axis Am direction, the struts correspond to this and move from the radially inner side toward the outer side. In general, the structure is inclined from the other side in the circumferential direction toward one side. However, as described above based on the graph of FIG. 4, when the gas turbine 100 is operated at a partial load, this configuration is not necessarily optimal for reducing pressure loss. It was obtained as a new finding by the inventor. Based on this knowledge, in this embodiment, the 1st strut 43 has taken the above structures.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to said 1st embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. As shown in the figure, in the diffuser 4 according to this embodiment, the configuration of the first strut 53 is different from that of the first embodiment. More specifically, the first surface S12 of the first strut 53 includes a first inclined surface T12 positioned relatively radially inward and a first outer inclined surface positioned radially outward of the first inclined surface T12. T13. The second surface S22 includes a second inclined surface T14 that is positioned relatively radially inward and a second outer inclined surface T15 that is positioned radially outward of the second inclined surface T14.

  The first inclined surface T12 extends from the outer peripheral surface 41A of the inner cylinder 41 toward the radially outer side. Specifically, the first inclined surface T12 extends from one circumferential side to the other side from the outer circumferential surface 41A of the inner cylinder 41 toward the radially outer side. On the other hand, the first outer inclined surface T13 extends from the other end in the circumferential direction toward one side from the radially outer end of the first inclined surface T12 toward the outer side in the radial direction.

  The second inclined surface T14 extends from the outer peripheral surface 41A of the inner cylinder 41 to the inner peripheral surface 42A of the outer cylinder 42 outward in the radial direction. Specifically, the second inclined surface T14 extends from the one side in the circumferential direction toward the other side from the outer circumferential surface 41A of the inner cylinder 41 toward the radially outer side. On the other hand, the second outer inclined surface T15 extends from the other side in the circumferential direction toward the one side as it goes from the radially outer end of the second inclined surface T14 to the outer side in the radial direction. That is, the first inclined surface T12 and the second inclined surface T14 extend in parallel to each other. Similarly, the first outer inclined surface T13 and the second outer inclined surface T15 extend in parallel to each other. Furthermore, in this embodiment, the extension dimension of the first outer inclined surface T13 is smaller than the extension dimension of the first inclined surface T12, and the extension dimension of the second outer inclined surface T15 is the extension of the second inclined surface T14. Smaller than current dimensions.

  According to such a structure, in addition to being able to suppress the separation of the flow on the outer peripheral surface 41A of the inner cylinder 41 by forming the first inclined surface T12, the first outer inclined surface T13 is formed. Accordingly, the separation of the flow on the inner peripheral surface 42A of the outer cylinder 42 can also be suppressed. More specifically, a vortex V2 as a horseshoe vortex including a component extending in the direction of the axis Am is formed in a region on one side in the circumferential direction of the first outer inclined surface T13. The vortex V2 flows toward the inner peripheral surface 42A of the outer cylinder 42 along the first outer inclined surface T13, and then moves toward the first outer inclined surface T13 again while being separated from the inner peripheral surface 42A. Flowing. That is, when viewed from one side in the direction of the axis Am, the vortex V2 is turning clockwise. Since the vortex V2 is formed, momentum is added to the boundary layer formed in the vicinity of the first outer inclined surface T13 in the region on one side in the circumferential direction of the first outer inclined surface T13. The flow of the exhaust gas is positively attached to the inner peripheral surface 42 </ b> A (radially outer side) of the outer cylinder 42. That is, it is possible to reduce the possibility that the exhaust gas flow is separated from the outer cylinder 42 on one side in the circumferential direction of the first outer inclined surface T13.

  In addition, since the vortex V2 is formed, the pressure in the region on one side in the circumferential direction of the first outer inclined surface T13 is higher than the pressure in the region on the other side in the circumferential direction of the second outer inclined surface T15. Thereby, the flow which goes to the other side from the circumferential direction one side across the first strut 53 is generated as in the first embodiment. Therefore, it is possible to reduce the possibility of the exhaust gas flow separating from the outer cylinder 42 also on the other circumferential side of the first strut 53. Thereby, the pressure loss in the exhaust flow path C by a flow peeling from the inner peripheral surface of the outer cylinder 42 can be suppressed.

  Furthermore, in the above-described configuration, the component flowing in the relatively radially inner region of the swirling flow swirling in the exhaust flow path C from the other circumferential side to the one side is applied to the second inclined surface T14. Along the radial direction from the outside to the inside. Thereby, a flow can be positively attached to the outer peripheral surface 41 </ b> A of the inner cylinder 41. That is, the separation of the flow on the outer peripheral surface 41A of the inner cylinder 41 can be further suppressed.

  Further, of the swirling flow in the exhaust passage C, a component that flows in a relatively radially outer region flows from the radially inner side toward the outer side along the second outer inclined surface T15. Thereby, the flow can be positively attached to the inner peripheral surface 42 </ b> A of the outer cylinder 42. That is, the separation of the flow on the inner peripheral surface 42A of the outer cylinder 42 can be further suppressed.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to said each embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. As shown in the figure, in the diffuser 4 according to the present embodiment, the configuration of the first strut 63 is different from the above embodiments. More specifically, in the first strut 63, the second outer inclined surface T15 in the second embodiment is not formed, and the entire second surface S23 extends from the outer peripheral surface of the inner cylinder 41 to the outer cylinder. The second inclined surface T34 extends uniformly over the inner peripheral surface of 42. The second inclined surface T34 extends from the outer circumferential surface 41A of the inner cylinder 41 toward the other side in the circumferential direction as it goes radially outward. On the other hand, in the first surface S13, as in the second embodiment, the first inclined surface T12 positioned relatively radially inward and the first inclined surface T12 positioned radially outward of the first inclined surface T12. One outer inclined surface T13 is formed. That is, in the radially outer portion of the first strut 63, the dimension in the circumferential direction is set larger than the other portions.

  According to such a configuration, similarly to the second embodiment, the outer peripheral surface 41A of the inner cylinder 41 and the inner periphery of the outer cylinder 42 are formed by forming the first inclined surface T12 and the first outer inclined surface T13. Flow separation from the surface 42A can be suppressed. In addition, since the entire second surface S23 is a second inclined surface T34 that extends uniformly, the radial dimension of the first strut 63 is larger in the circumferential direction than the other portions. ing. Thereby, the rigidity of the 1st strut 63 can be raised compared with the structure by which the dimension in the circumferential direction of the 1st strut 63 is made the same over the whole region of radial direction, for example. That is, even when an external force is applied to the first strut 63, the external force can be sufficiently resisted.

  The embodiments of the present invention have been described above with reference to the drawings. Note that the configurations described in the above embodiments are merely examples, and various modifications can be made to the configurations without departing from the gist of the present invention.

  For example, in each of the above-described embodiments, the configuration in which six first struts 43 (first struts 53 and first struts 63) are provided has been described. However, the number of the first struts 43 (first struts 53, first struts 63) is not limited depending on the above-described embodiment, and may be appropriately determined according to the design and specifications.

  Further, in each of the above embodiments, the configuration in which the second strut 44 is provided on the other side in the axis Am direction of the first strut 43 has been described. However, when the outer cylinder 42 can be stably supported and fixed with respect to the inner cylinder 41, the second strut 44 is not necessarily provided, and the first strut 43 (first strut 53, first strut). 63) alone may be provided.

  In addition, the configuration of the inner cylinder 41 is not limited depending on the embodiment. In particular, in the above-described embodiment, the example in which the inner cylinder 41 is configured to reduce the diameter from one side to the other side in the axis Am direction has been described. However, the inner cylinder 41 is not necessarily configured as described above, and may extend in parallel to the axis Am. Even if it is such a structure, if the outer cylinder 42 is diameter-expanded toward the other side from the one side of the axis Am direction, the function as the diffuser 4 can be exhibited.

  In addition, in the second embodiment, the first inclined surface T12 and the first outer inclined surface T13 are connected to each other, and the second inclined surface T14 and the second outer inclined surface T15 are connected to each other. explained. However, another surface extending in the radial direction, for example, may be formed between the first inclined surface T12 and the first outer inclined surface T13. Similarly, for example, another surface extending in the radial direction may be formed between the second inclined surface T14 and the second outer inclined surface T15.

DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Turbine 3 ... Combustor 4 ... Diffuser 11 ... Compressor rotor 12 ... Compressor casing 13 ... Compressor blade stage 14 ... Compressor blade 15 ... Compressor stationary blade stage 16 ... Compressor stationary blade 21 ... Turbine rotor 22 ... Turbine casing 23 ... Turbine rotor blade stage 24 ... Turbine rotor blade 25 ... Turbine stator blade stage 26 ... Turbine stator blade 41 ... Inner cylinder 41A ... Outer surface 42 of inner cylinder ... Outer cylinder 42A ... Inner circumference of outer cylinder Surfaces 43, 53, 63 ... first strut (strut)
44 ... Second strut 91 ... Gas turbine rotor 91A ... Shaft end 92 ... Gas turbine casing 100 ... Gas turbine Am ... Axis C ... Exhaust flow path G ... Generators S1, S12, S13 ... First surface S2, S22, S23 ... 2nd surface T1, T12 ... 1st inclined surface T13 ... 1st outer side inclined surface T2, T14, T34 ... 2nd inclined surface T15 ... 2nd outer side inclined surface V1, V2 ... vortex

Claims (6)

A turbine rotor that extends along an axis and is rotatable toward one circumferential side of the axis;
A turbine casing that covers the turbine rotor from an outer peripheral side;
A plurality of turbine rotor blades arranged in a circumferential direction of the axis on the outer peripheral surface of the turbine rotor, wherein at least a portion on the other side in the axial direction is curved from one side in the circumferential direction to the other side;
A plurality of turbine stationary blades arranged adjacent to the turbine rotor blade in the axial direction on the inner peripheral surface of the turbine casing, and arranged in the circumferential direction;
A diffuser that is provided on the other axial side of the turbine rotor blade and that defines an exhaust passage through which exhaust gas flows from one axial direction to the other;
With
The diffuser is
An inner cylinder extending along the axis;
An outer cylinder that covers the inner cylinder from the outer periphery side and that defines the exhaust passage between the inner cylinder;
A plurality of struts that are provided at intervals in the circumferential direction in the exhaust flow path, connect the inner cylinder and the outer cylinder, and are formed with a first surface facing one side in the circumferential direction,
Have
The first surface is
A turbine having a first inclined surface extending from one side in the circumferential direction toward the other side in the radial direction from the outer circumferential surface of the inner cylinder.   The first surface has a first outer inclined surface that is provided on the radially outer side of the first inclined surface and extends from the other side in the circumferential direction toward the one side as it goes from the radially inner side to the outer side. The turbine described in 1. The strut is formed with a second surface facing the other side in the circumferential direction,
The turbine according to claim 1 or 2, wherein the second surface has a second inclined surface extending from one side in the circumferential direction toward the other side in the radial direction from the outer circumferential surface of the inner cylinder.   The second surface is provided on the radially outer side of the second inclined surface, and has a second outer inclined surface extending from the other circumferential side toward the one side as it goes from the radially inner side to the outer side. The turbine described in 1.   The turbine according to claim 3, wherein the second inclined surface extends from an outer peripheral surface of the inner cylinder to an inner peripheral surface of the outer cylinder. A compressor that generates high-pressure air;
A combustor that generates high-temperature and high-pressure combustion gas by mixing and fueling the high-pressure air; and
A gas turbine comprising: the turbine according to claim 1 driven by the combustion gas.

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