JP2018105221A - Diffuser, turbine and gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress pressure loss to improve performance.SOLUTION: A diffuser 4A includes: an inner cylinder 41; an outer cylinder configured to form an exhaust flow passage between itself and the inner cylinder 41; a plurality of struts 43A provided in a circumferential direction at intervals in the exhaust flow passage, connecting the inner cylinder 41 and the outer cylinder, and extending on a forward side of a rotational direction of a turbine from radial inside to radial outside; and a projection part 50 formed on an outer peripheral surface 41A of the inner cylinder 41, arranged at a center between a pair of struts 43A adjacent in the circumferential direction, and arranged in a region within ±10% of the entire length in an axial Am direction of a first strut 43 with a position of a front edge 43a of the strut 43 in the axial Am direction as reference.SELECTED DRAWING: Figure 3

Description

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

In general, a gas turbine includes a compressor, a combustor, and a turbine. The compressor compresses outside air to generate high-pressure air, and the combustor generates high-temperature and high-pressure combustion gas by mixing and burning high-pressure air and fuel generated by the compressor. The turbine is driven by the combustion gas generated by this combustor.
A diffuser is provided on the downstream side of the turbine (see, for example, Patent Document 1). Some diffusers include an inner cylinder, an outer cylinder, and a strut. The inner cylinder is disposed on the inner peripheral side of the diffuser, and the outer cylinder forms an exhaust passage between the inner cylinder and the inner cylinder by covering the inner cylinder from the outer peripheral side. A plurality of struts are provided at intervals in the circumferential direction, and each strut extends from the outer circumferential surface of the inner cylinder in the radial direction of the turbine. The inner cylinder and the outer cylinder are connected via these struts.
The exhaust passage of the diffuser is formed such that the passage area gradually increases from upstream to downstream in the direction in which the combustion gas flows. The combustion gas (exhaust gas) that has driven the turbine is recovered by static pressure by passing through the exhaust passage formed in this way. When the performance of the diffuser is improved, the pressure ratio of the gas turbine is substantially increased. Therefore, the improvement of the performance of the diffuser also contributes to the improvement of the efficiency of the entire gas turbine.

Japanese Patent No. 5693315

  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 around the axis. Therefore, when the flow of exhaust gas passes around the strut, shape resistance is generated by the strut or separation of the flow occurs. These shape resistance and flow separation are factors that increase pressure loss. This increase in pressure loss may reduce the static pressure recovery amount of the diffuser and reduce the overall efficiency of the gas turbine.

  The present invention has been made in view of the above circumstances, and provides a diffuser, a turbine, and a gas turbine that can suppress pressure loss and improve performance.

In order to solve the above problems, the following configuration is adopted.
According to the first aspect of the present invention, the diffuser is a diffuser provided on the downstream side of the turbine rotating around the axis, and covers the inner cylinder extending along the axis from the outer peripheral side, An outer cylinder that forms an exhaust passage between the inner cylinder and the inner cylinder is provided with a circumferential interval in the exhaust passage, and connects the inner cylinder and the outer cylinder, and from the radially inner side. A plurality of struts extending forward in the rotational direction of the turbine as it goes outward, and arranged on the outer peripheral surface of the inner cylinder, arranged in the center between a pair of struts adjacent in the circumferential direction, And a convex portion disposed in a region of ± 10% of the total length of the strut in the axial direction with respect to the position of the front edge on one side in the axial direction.
In the diffuser, the flow between struts adjacent in the circumferential direction around the axis generally forms a boundary layer on the outer peripheral surface of the inner cylinder. Since the diffuser flow is an inverse pressure gradient, the momentum tends to decrease in the boundary layer flow. Therefore, when a separation region due to a local momentum defect occurs, separation may progress toward the downstream side of the flow and become larger.
In general, upstream of the strut, the boundary layer is disturbed due to the flow of the seal gas through the gap between the rotating body and the diffuser, and becomes unstable. Further, the vorticity in the direction perpendicular to the flow direction is increased. By arranging the above-mentioned convex part in the boundary layer, the fluid in the boundary layer is wound around the convex part, and a vertical vortex having a vortex axis in the fluid flow direction is formed on both sides in the circumferential direction of the convex part. Is done. This vertical vortex extends downstream from the convex portion to form a vortex tube (horse-shoe vortex). Thereby, since a stable vertical vortex can be generated on the outer peripheral surface of the inner cylinder, momentum is given to the fluid in the boundary layer by the vertical vortex, and the occurrence of separation due to the development of the boundary layer can be suppressed. As a result, pressure loss can be suppressed and performance can be improved.

According to the second aspect of the present invention, the diffuser according to the first aspect may include a guide plate extending in the axial direction with a space downstream from the convex portion.
By comprising in this way, while maintaining the vertical vortex formed by the convex part to the downstream side, the disturbance of the vertical vortex can be adjusted (rectified).

According to the third aspect of the present invention, the convex portion according to the first aspect is within a region of ± 5% of the total length in the axial direction of the strut with reference to the position of the front edge on one side in the axial direction of the strut. It may be arranged.
By comprising in this way, a convex part can be arrange | positioned in the position nearer to the position of the front edge of a strut. Thereby, before a boundary layer develops, a vertical vortex can be produced by a convex part and momentum can be given to the fluid in a boundary layer. As a result, the development of the boundary layer can be stably suppressed.

According to the fourth aspect of the present invention, the convex portion according to any one of the first to third aspects may be formed to taper toward the outside in the radial direction centering on the axis.
By comprising in this way, it can suppress that a shape resistance increases with respect to the mainstream of a diffuser. As a result, pressure loss can be reduced.

According to the fifth aspect of the present invention, the diffuser is a diffuser provided on the downstream side of the turbine rotating around the axis, and covers the inner cylinder extending along the axis from the outer peripheral side, An outer cylinder that forms the exhaust flow path between the inner cylinder and the inner cylinder is provided with a circumferential interval in the exhaust flow path, and connects the inner cylinder and the outer cylinder and is radially inward. A plurality of struts extending forward in the rotational direction of the turbine from the outside to the outside, and formed on the outer peripheral surface of the inner cylinder and disposed in the center between a pair of adjacent struts in the circumferential direction, and in the axial direction And a guide convex portion extending from the region of ± 10% of the total length in the axial direction of the strut to the rear edge position of the strut with reference to the front edge position of the strut.
With this configuration, the fluid in the boundary layer wraps around the guide convex portion on the side close to the front edge of the strut, and the vortex axis is formed in the fluid flow direction on both sides in the circumferential direction of the guide convex portion. A longitudinal vortex is formed. This vertical vortex extends downstream from the guide convex portion to form a vortex tube (horse-shoe vortex). Thereby, a stable vertical vortex can be generated on the outer peripheral surface of the inner cylinder. Furthermore, since the guide convex portion continuously extends to the rear edge position of the strut, the convex portion can function as a guide plate. That is, it is possible to arrange (rectify) the disturbance of the vertical vortex while maintaining the vertical vortex to the downstream side by the guide convex portion. As a result, momentum is given to the fluid in the boundary layer by the vertical vortex, and the boundary layer can be prevented from developing and causing separation. As a result, pressure loss can be suppressed and performance can be improved.

According to a sixth aspect of the present invention, the turbine extends along the axis and is rotatable toward one side in the circumferential direction of the axis, the turbine casing covering the turbine rotor from the outer periphery side, A plurality of turbine rotor blades arranged in the circumferential direction of the axis on the outer peripheral surface of the turbine rotor, and provided adjacent to the turbine rotor blade in the axial direction on the inner peripheral surface of the turbine casing And a plurality of turbine stationary blades arranged in the circumferential direction, and a diffuser according to any one of the first to fifth aspects.
By comprising in this way, since the peeling of the fluid in a diffuser can be suppressed, the pressure loss of a turbine can be suppressed. As a result, the kinetic energy of the exhaust gas discharged from the turbine can be efficiently converted into pressure energy.

According to a seventh aspect of the present invention, the gas turbine is driven by the compressor that generates compressed air obtained by compressing air, the combustor that generates fuel by mixing fuel with the compressed air, and the combustion gas. A turbine according to a sixth aspect of the present invention.
By comprising in this way, since the pressure loss of a turbine can be suppressed, the performance of a gas turbine can be improved.

  According to the diffuser, turbine, and gas turbine, it is possible to suppress pressure loss and improve performance.

It is a block diagram which shows schematic structure of the gas turbine in 1st embodiment of this invention. It is sectional drawing which follows the axis line of the diffuser in 1st embodiment of this invention. It is a perspective view of the inner cylinder between the adjacent 1st struts in 1st embodiment of this invention. It is the figure which looked at the vortex around the convex part in 1st Embodiment of this invention from the one side of the axial direction. It is a figure equivalent to FIG. 3 in 2nd embodiment of this invention. It is a figure equivalent to FIG. 3 in 3rd embodiment of this invention.

(First embodiment)
Next, a turbine and a gas turbine according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing a schematic configuration of a gas turbine according to a first embodiment of the present invention.
As shown in FIG. 1, a gas turbine 100 according to the first embodiment includes a compressor 1, a combustor 3, and a turbine 2A.

  The compressor 1 generates high-pressure air. The compressor 1 includes a compressor rotor 11 and a compressor casing 12. The compressor casing 12 covers the compressor rotor 11 from the outer peripheral side, and extends along the axis Am.

  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 of the compressor blade stages 13 includes a plurality of compressor blades 14. The compressor blades 14 of each compressor blade stage 13 are 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. These compressor stationary blade stages 15 are arranged alternately with the compressor moving blade stages 13 in the direction of the axis Am. Each of the compressor vane stages 15 includes a plurality of compressor vanes 16. The compressor vanes 16 of each compressor vane stage 15 are arranged on the inner circumferential surface of the compressor casing 12 at intervals in the circumferential direction of the axis Am.

  The combustor 3 generates combustion gas by mixing the high-pressure air generated by the compressor 1 and burning the fuel. The combustor 3 is provided between the compressor casing 12 and the turbine casing 22 of the turbine 2A. The combustion gas generated by the combustor 3 is supplied to the turbine 2A.

The turbine 2 </ b> A is driven by the combustion gas generated by the combustor 3. The turbine 2A includes a turbine rotor 21, a turbine casing 22, and a diffuser 4A.
The turbine rotor 21 extends along the axis Am. 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 of these turbine blade stages 23 includes a plurality of turbine blades 24. The turbine rotor blades 24 of the turbine rotor blade stages 23 are arranged on the outer peripheral surface of the turbine rotor 21 at intervals in the circumferential direction of the axis Am.

  Among the plurality of turbine rotor blade stages 23, the turbine rotor blade 24 constituting the final stage turbine rotor blade stage 23 arranged on the most downstream side has a portion on the other side in the axis Am direction around the axis Am. Curved from one side of the direction to the other. In other words, the turbine blade 24 of the turbine blade stage 23 in the final stage is curved so that the downstream edge portion (rear edge) faces the rear side in the rotational direction of the turbine rotor 21. Note that at least the turbine blade 24 of the turbine blade stage 23 in the final stage only needs to be curved as described above, and is not limited to the above configuration. For example, the turbine blades 24 of other turbine blade stages 23 may be curved in the same manner as the turbine blades 24 of the final turbine blade stage 23.

  The turbine casing 22 covers the turbine rotor 21 from the outer peripheral side. A plurality of turbine vane stages 25 arranged at intervals in the direction of the axis Am are provided on the inner peripheral surface of the turbine casing 22. The turbine stationary blade stages 25 are arranged alternately with the turbine rotor blade stages 23 in the axis Am direction. Each of these turbine stationary blade stages 25 includes a plurality of turbine stationary blades 26. The turbine stationary blades 26 of each turbine stationary blade stage 25 are 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. The compressor rotor 11 and the turbine rotor 21 constitute a gas turbine rotor 91. Similarly, the compressor casing 12 and the turbine casing 22 are integrally connected along the axis Am. The compressor casing 12 and the turbine casing 22 constitute a gas turbine casing 92.
The gas turbine rotor 91 is integrally rotatable around the axis Am within the gas turbine casing 92.

  In operating the gas turbine 100, 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. The combustion gas is supplied into the turbine 2 </ b> A through the turbine casing 22. In the turbine 2A, 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 applied to the turbine rotor 21 (gas turbine rotor 91). This rotational energy is used, for example, for driving the generator G connected to the shaft end. The combustion gas that has driven the turbine 2A is discharged to the outside after the pressure (static pressure) is increased when passing through the diffuser 4A as exhaust gas.

FIG. 2 is a sectional view taken along the axis of the diffuser in the first embodiment of the present invention.
As shown in FIG. 2, the diffuser 4A is provided integrally with the turbine casing 22 (gas turbine casing 92). The diffuser 4A includes an inner cylinder 41, an outer cylinder 42, a first strut 43, a second strut 44, and a convex portion 50 (see FIG. 3).

  The inner cylinder 41 is formed in a cylindrical shape extending along the axis Am. The inner cylinder 41 is formed such that its outer peripheral surface 41A gradually decreases in diameter from one side to the other side in the axis Am direction. Inside the inner cylinder 41, a bearing device 30 that rotatably supports the shaft end portion 91A of the gas turbine rotor 91 is provided. The bearing device 30 includes a bearing 31 and a bearing housing 32. The bearing housing 32 is mainly supported by the outer cylinder 42 by the first struts 43.

  The outer cylinder 42 is formed in a cylindrical shape that covers the inner cylinder 41 from the outer peripheral side. The outer cylinder 42 forms an exhaust passage C between which the exhaust gas discharged from the turbine 2A flows. The outer cylinder 42 is formed such that its inner peripheral surface 42A gradually increases in diameter from one side to the other side in the axis Am direction. That is, the cross-sectional area of the exhaust passage C formed between the outer cylinder 42 and the inner cylinder 41 (cross-sectional area perpendicular to the axis Am) gradually increases in diameter as it goes from one side to the other in the axis Am direction. doing. As the cross-sectional area of the exhaust passage C gradually increases in this way, the kinetic energy of the exhaust gas flowing through the exhaust passage C is gradually converted into pressure energy (pressure recovery).

  The first strut 43 is covered with a strut cover 45 so as not to be exposed to high-temperature exhaust gas. As the first strut 43, a so-called tangential strut inclined with respect to the normal line of the outer peripheral surface 41A of the inner cylinder 41 can be used. By adopting such a tangential strut, it is possible to reduce the shift of the axial center due to thermal elongation.

  The second strut 44 functions as a passage that distributes the load burden of the first strut 43 and enables a person to enter the bearing 31 of the gas turbine 100, for example. The second strut 44 is formed in a cylindrical shape extending in the radial direction around the axis Am. The second strut 44 is provided at a position spaced from the first strut 43 on the other side in the axis Am direction.

  The strut cover 45 and the second strut 44 in the first embodiment have a shape that can reduce the shape resistance against the exhaust gas. Examples of the shape that can reduce the shape resistance to the exhaust gas include an elliptical cross section that is long in the direction in which the exhaust gas flows, and a blade shape in which the chord extends in the direction in which the exhaust gas flows.

  The gas turbine 100 includes a sealing mechanism (not shown). This sealing mechanism causes a portion of the compressed air generated by the compressor 1 to flow into the exhaust passage C from the gap between the above-described inner cylinder 41 of the diffuser 4A and the turbine rotor 21 as a sealing gas. Yes. This sealing mechanism prevents the exhaust gas from flowing out from the gap.

FIG. 3 is a perspective view of an inner cylinder between adjacent first struts in the first embodiment of the present invention.
As shown in FIG. 3, the diffuser 4 </ b> A includes a convex portion 50 between first struts 43 (strut covers 45) that are adjacent in the circumferential direction about the axis Am. One convex portion 50 is provided between each of the plurality of first struts 43 arranged side by side in the circumferential direction. The convex portion 50 protrudes from the outer peripheral surface 41 </ b> A of the inner cylinder 41. The convex portion 50 in the first embodiment protrudes from the outer peripheral surface 41A toward the outside in the radial direction with the axis Am as the center.

  Here, the protrusion amount (in other words, the radial height) of the protrusion 50 is slightly smaller than the thickness of the boundary layer (not shown) formed on the outer peripheral surface 41A of the inner cylinder 41 by the flow of exhaust gas. Can be lowered. More specifically, the protrusion amount of the protrusion 50 may be a protrusion amount of 5% with respect to the height (blade height) of the first strut 43 in the radial direction around the axis Am. Further, the protruding amount of the convex portion 50 may be 3% with respect to the height of the first strut 43. Further, the protruding amount of the convex portion 50 may be 1% with respect to the height of the first strut 43. In addition, since the thickness of the boundary layer changes according to the specification of the diffuser 4A, the protruding amount of the convex portion 50 may be appropriately adjusted according to the thickness of the boundary layer.

  The convex portion 50 in the first embodiment is formed at the center (50%) of the adjacent first struts 43 when the distance between the adjacent first struts 43 is 100% in the circumferential direction around the axis Am. It can be formed within a range of ± 30% from the position. Furthermore, the convex portion 50 may be arranged at a position of ± 20% from the position of the center (50%) in the circumferential direction around the axis Am. Furthermore, the convex part 50 may be arranged at a position ± 10% from the position of the center (50%) in the circumferential direction around the axis Am.

  Further, when the total length of the first strut 43 in the axis Am direction is 100%, the convex portion 50 has a front edge (in other words, an edge portion on one side in the axis Am direction) 43a of the first strut 43 in the axis Am direction. The position (hereinafter, simply referred to as “the position of the leading edge”. The position indicated by a two-dot chain line F in FIG. 3) can be disposed in a region of ± 10% of the total length of the first strut 43. Further, the convex portion 50 may be arranged in a region of ± 5% with respect to the position of the front edge in the axis Am direction. Further, the convex portion 50 may be arranged in a region of ± 3% with respect to the position of the front edge in the axis Am direction. Further, the convex portion 50 may be arranged in a region of ± 2% with respect to the position of the front edge in the axis Am direction.

  The length of the convex portion 50 in the direction of the axis Am may be any length as long as it falls within the above-described region with respect to the position of the front edge 43a. For example, you may form in the length equivalent to the length of the said area | region in the axis line Am direction.

  The convex portion 50 may be formed to be tapered toward the outer side in the radial direction centering on the axis Am. In FIG. 3, as an example of the taper shape, a case in which the protruding amount of the convex portion 50 is increased from one side (upstream side) in the axis Am direction toward the other side (downstream side) is illustrated. However, it is not limited to this shape as long as it is tapered.

  By the way, when the gas turbine 100 is operated, the seal gas may flow inward in the radial direction around the axis Am at the inlet of the diffuser 4A. This seal gas interferes with the flow in the unstable boundary layer formed on the outer peripheral surface 41 </ b> A of the inner cylinder 41. Here, the flow in the boundary layer is primarily a secondary flow typified by a horseshoe vortex generated at the joint between the first strut 43 and the outer peripheral surface 41A of the inner cylinder 41, or a pressure due to the circumferential inclination of the first strut 43. Due to the gradient, the flow becomes a three-dimensional flow, and separation tends to occur when the disturbance increases. The flow in the boundary layer increases the vorticity in the vertical direction due to the inflow of the seal gas. That is, the flow in the boundary layer mainly includes the vortex V2 (see FIG. 3) having a circumferential vortex axis centered on the axis Am. The boundary layer with increased vorticity in the vertical direction is greatly developed as it proceeds downstream as compared with the case where seal gas does not flow. In particular, since the cross-sectional area of the flow path suddenly expands with the position of the rear edge 43b of the first strut 43 as a boundary, there is a possibility that the flow velocity is further reduced and boundary layer separation occurs.

  As described above, in the diffuser 4A of the first embodiment, the convex portion 50 is disposed between the first struts 43 adjacent in the circumferential direction with the axis Am as the center. These convex portions 50 are arranged near the position of the front edge 43a of the first strut 43 in the direction of the axis Am. The flow in the boundary layer having the vertical vorticity due to the interference of the sealing gas described above is wound around the convex portion 50 near the position of the front edge 43a of the first strut 43.

  Thereby, the vertical vortex V3 having a vortex axis in the direction in which the exhaust gas flows is formed on both sides of the convex portion 50 in the circumferential direction. The vertical vortex V3 extends downstream from the convex portion 50 to form a vortex tube. The vertical vortex V3 gives momentum to the exhaust gas in the boundary layer downstream of the vicinity of the front edge 43a of the first strut 43. Therefore, even when the seal gas flows in as described above, momentum is given to the flow in the boundary layer before the boundary layer develops, so that the boundary layer develops and so-called boundary layer separation is suppressed. it can. As a result, it is possible to improve the performance by suppressing the pressure loss of the diffuser 4A.

FIG. 4 is a view of the vortex around the protrusion in the first embodiment of the present invention as viewed from one side in the axial direction.
As shown in FIG. 4, the vertical vortex V3 rotates in the opposite direction to the adjacent horseshoe vortex V1. As described above, the rotation directions of the vertical vortex V3 and the horseshoe vortex V1 are opposite to each other, so that the flow of the vertical vortex V3 and the flow of the horseshoe vortex V1 flow in the same direction at adjacent locations. The vertical vortex V3 and the horseshoe vortex V1 are stabilized. Therefore, the vertical vortex V3 and the horseshoe vortex V1 are easily maintained even downstream of the first strut 43, and the development of the boundary layer can be further suppressed.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. This second embodiment is different only in that a guide plate is provided in the first embodiment described above. Therefore, the same portions as those in the first embodiment described above are described with the same reference numerals, and redundant descriptions are omitted.
The gas turbine 100 according to the second embodiment includes the compressor 1, the combustor 3, and the turbine 2B as in the first embodiment described above. Further, the turbine 2B includes a turbine rotor 21, a turbine casing 22, and a diffuser 4B.

FIG. 5 is a view corresponding to FIG. 3 in the second embodiment of the present invention.
As shown in FIG. 5, the diffuser 4 </ b> B in the second embodiment includes an inner cylinder 41, an outer cylinder 42 (not shown in FIG. 5), a first strut 43, a second strut 44, and a convex portion 50. And a guide plate 51.
The convex part 50 is the structure similar to 1st embodiment, and is each provided between the some 1st struts 43 arrange | positioned along with the circumferential direction centering on the axis line Am. These convex portions 50 protrude from the outer peripheral surface 41 </ b> A of the inner cylinder 41.

  The guide plate 51 guides the vertical vortex V3 generated at the convex portion 50 to the downstream side. As with the convex portion 50, one guide plate 51 is provided between each of the plurality of first struts 43 arranged side by side in the circumferential direction with the axis Am as the center. These guide plates 51 are formed so as to extend in the direction of the axis Am, and are arranged at a distance from the convex portion 50 on the downstream side in the direction in which the exhaust gas flows.

  The guide plate 51 is further formed so as to protrude from the outer peripheral surface 41A of the inner cylinder 41 toward the radially outer side centering on the axis Am. The guide plate 51 exemplified in this second embodiment is formed in a flat plate shape extending toward the radially outer side. Further, the guide plate 51 exemplified in the second embodiment is formed so that the protruding amount gradually increases from one side in the axis Am direction toward the other side. The guide plate 51 may have a maximum protrusion amount equal to the protrusion amount of the protrusion 50.

  The guide plate 51 exemplified in the second embodiment has a position of 50% with respect to the chord length of the first strut 43 with respect to the leading edge 43a of the first strut 43 (in other words, the leading edge in the direction of the axis Am). 43a and the rear edge 43b) to the position of the rear edge 43b of the first strut 43. In FIG. 5, the position of the rear edge 43 b is indicated by “R”, and the intermediate position of the front edge 43 a and the rear edge 43 b is indicated by “M”.

The thickness (dimension) of the guide plate 51 in the circumferential direction around the axis Am is formed to be equal to the dimension of the convex portion 50 in the circumferential direction around the axis Am.
In addition, as shown with a broken line in FIG. 5, the guide plate 51 may extend to the downstream side of the position of the rear edge 43b. By doing in this way, it can suppress that the flow-path cross-sectional area of exhaust gas expands suddenly rather than the position of the rear edge 43b of the 1st strut 43. FIG. Further, the positions of the upstream end and the downstream end in the direction of the axis Am of the guide plate 51 in the second embodiment are examples, and positions where the vertical vortex V3 formed by the convex portion 50 can be guided. If it is, it will not be restricted to said position.

  According to the second embodiment described above, the vertical vortex V3 can be formed by the convex portion 50 as in the first embodiment. Furthermore, by providing the guide plate 51, the vertical vortex V3 formed by the convex portion 50 can be maintained further downstream, and the disturbance of the vertical vortex V3 can be adjusted (rectified).

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings. This third embodiment is different only in that the convex portion and the guide plate of the second embodiment described above are provided integrally. For this reason, the same portions as those in the second embodiment described above are denoted by the same reference numerals and redundant description is omitted.
The gas turbine 100 according to the third embodiment includes the compressor 1, the combustor 3, and the turbine 2C as in the first embodiment described above. Further, the turbine 2C includes a turbine rotor 21, a turbine casing 22, and a diffuser 4C.

FIG. 6 is a view corresponding to FIG. 3 in the third embodiment of the present invention.
As shown in FIG. 6, the diffuser 4C according to the third embodiment includes an inner cylinder 41, an outer cylinder 42 (not shown in FIG. 6), a first strut 43, a second strut 44, and a guide projection. 52.

One guide convex portion 52 is provided between each of the plurality of first struts 43 arranged side by side in the circumferential direction around the axis Am.
In the circumferential direction centering on the axis Am, the guide convex portion 52 in the third embodiment has a center (50%) of the adjacent first struts 43 when the distance between the adjacent first struts 43 is 100%. It can be formed within a range of ± 30% from the position of. Further, the guide convex portion 52 may be arranged at a position of ± 20% from the position of the center (50%) in the circumferential direction around the axis Am. Furthermore, the convex part 50 may be arranged at a position ± 10% from the position of the center (50%) in the circumferential direction around the axis Am.

  The guide protrusions 52 are arranged at positions near the front edge 43a of the first strut 43 in the axis Am direction in the upstream end (end in the axis Am direction) of the guide plate 51 of the second embodiment described above. Thus, the shape is such that the length in the direction of the axis Am is extended. That is, these guide convex parts 52 are formed so as to extend in the axis Am direction.

  The guide convex portion 52 extends from the region of ± 10% of the total length of the strut 43 in the axis Am direction to the position of the rear edge 43b of the first strut 43 with respect to the position of the front edge 43a of the first strut 43 in the axis Am direction. It extends towards. The guide protrusion 52 extends from the region of ± 5% of the total length in the axis Am direction of the first strut 43 toward the position of the rear edge 43b of the first strut 43 with reference to the position of the front edge 43a. May be. Further, the guide convex portion 52 is located at the position of the rear edge 43b of the first strut 43 from within a region of ± 3% of the total length of the first strut 43 in the axis Am direction with reference to the position of the front edge 43a of the first strut 43. You may extend toward.

  The guide convex portion 52 is further formed so as to protrude from the outer peripheral surface 41A of the inner cylinder 41 toward the radially outer side centering on the axis Am. The guide projection 52 exemplified in the third embodiment is formed in a flat plate shape extending outward in the radial direction. Moreover, the guide convex part 52 illustrated in this third embodiment is formed so that the protruding amount gradually increases from one side (upstream side) in the axis Am direction toward the other side (downstream side). The maximum protrusion amount of the guide convex portion 52 can be formed to the same extent as the convex portion 50 of the first embodiment described above.

  Therefore, according to the third embodiment, the seal gas interferes and the flow in the boundary layer having the vertical vorticity winds around the guide convex portion 52, and the vertical vortex V3 can be formed. Further, the guide convex portion 52 extends to the position of the rear edge 43b of the first strut 43 in the axis Am direction, so that the vertical vortex V3 formed by the guide convex portion 52 is downstream along the guide convex portion 52. And the disturbance of the vertical vortex V3 can be corrected.

The present invention is not limited to the configuration of each of the embodiments described above, and the design can be changed without departing from the gist thereof.
For example, in the second and third embodiments described above, the case where the guide plate 51 and the guide convex portion 52 are each plate-shaped has been described. However, the shape is not limited to a plate shape, and for example, it may have an airfoil shape or may be tapered toward the outside in the radial direction with the axis Am as the center.
Furthermore, although the guide plate 51 and the guide convex part 52 demonstrated the case where it formed so that protrusion amount might increase gradually toward the other side (downstream side) from the one side (upstream side) of an axis Am direction. The shape is not limited to this. For example, the protruding amount may be uniform from the upstream side toward the downstream side.

  Moreover, in each embodiment mentioned above, the case where the convex part 50, the guide plate 51, and the guide convex part 52 were each formed between the 1st struts 43 adjacent in the circumferential direction was demonstrated. However, two or more convex portions 50, guide plates 51, and guide convex portions 52 may be formed between the first struts 43 adjacent in the circumferential direction.

  Furthermore, in 1st embodiment, the case where all the some convex parts 50 provided in one diffuser 4A were the same structures was demonstrated. However, the plurality of convex portions 50 may have different configurations (shape, arrangement, etc.). For example, the position, length, height, and width of the convex portion 50 may be different for each of the plurality of convex portions 50. Similarly, the plurality of guide plates 51 of the second embodiment and the plurality of guide protrusions 52 of the third embodiment provided in one diffuser may have different configurations (shape, arrangement, etc.).

DESCRIPTION OF SYMBOLS 1 Compressor 2A, 2B, 2C Turbine 3 Combustor 4A, 4B, 4C 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 30 Bearing device 31 Bearing 32 Bearing housing 41 Inner cylinder 41A Outer surface 42 Outer cylinder 42A Inner surface 43 First strut (strut)
43a front edge 43b rear edge 44 second strut 45 strut cover 50 convex portion 51 guide plate 52 guide convex portion 91 gas turbine rotor 91A shaft end portion 92 gas turbine casing 100 gas turbine Am axis C exhaust passage G generator V1 horseshoe vortex V2 Vortex V3 Longitudinal vortex

Claims (7)

A diffuser provided downstream of a turbine rotating about an axis;
An inner cylinder extending along the axis;
An outer cylinder that covers the inner cylinder from the outer peripheral side and forms an exhaust passage between the inner cylinder and the inner cylinder;
A plurality of struts that are provided in the exhaust flow passage at intervals in the circumferential direction, connect the inner cylinder and the outer cylinder, and extend forward in the rotational direction of the turbine from the radially inner side toward the outer side. When,
The overall length in the axial direction of the strut formed on the outer peripheral surface of the inner cylinder and disposed in the center between a pair of struts adjacent to each other in the circumferential direction, with reference to the position of the leading edge on one side in the axial direction of the strut Convex portions arranged in an area of ± 10% of
Diffuser with.   The diffuser according to claim 1, further comprising a guide plate extending in an axial direction with a space on a downstream side of the convex portion.   2. The diffuser according to claim 1, wherein the convex portion is disposed in a region of ± 5% of the total length in the axial direction of the strut with reference to a position of a front edge on one side in the axial direction of the strut.   The diffuser according to any one of claims 1 to 3, wherein the convex portion is formed to taper toward an outer side in a radial direction centering on an axis. A diffuser provided downstream of a turbine rotating about an axis;
An inner cylinder extending along the axis;
An outer cylinder that covers the inner cylinder from the outer peripheral side and forms an exhaust passage between the inner cylinder and the inner cylinder;
A plurality of struts that are provided in the exhaust flow passage at intervals in the circumferential direction, connect the inner cylinder and the outer cylinder, and extend forward in the rotational direction of the turbine from the radially inner side toward the outer side. When,
It is formed on the outer peripheral surface of the inner cylinder and is arranged at the center between a pair of struts adjacent in the circumferential direction, and is ± 10 of the total length in the axial direction of the strut in the axial direction with reference to the front edge position of the strut %, And a guide convex portion extending from the area of% to the rear edge position of the strut. 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 the circumferential direction of the axis on the outer peripheral surface of the turbine rotor;
A plurality of turbine stationary blades arranged in the circumferential direction on the inner peripheral surface of the turbine casing so as to be adjacent to the turbine rotor blade in the axial direction;
A diffuser according to any one of claims 1 to 5;
Turbine with. A compressor that generates compressed air obtained by compressing air;
A combustor that mixes fuel with the compressed air to generate combustion gas;
The turbine according to claim 6 driven by the combustion gas;
A gas turbine comprising:

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