Centrifugal rotary machine

1. A centrifugal rotary machine comprising:

impellers which are provided in a plurality of stages along an axial direction and discharge a working fluid sucked from a first side in the axial direction to an outside in a radial direction of an axis; and

a casing which is provided to surround the impellers and forms a flow path which leads the working fluid discharged from an upstream-side impeller positioned on the first side in the axial direction to a downstream-side impeller positioned on a second side in the axial direction,

wherein the flow path includes

a return bend portion which guides the working fluid to an inside in the radial direction by reversing the working fluid discharged to an outside in the radial direction from the upstream-side impeller, and

a guiding flow path which is connected to a downstream side of the return bend portion and leads the working fluid to the inside in the radial direction so as to guide the working fluid to the downstream-side impeller,

wherein the centrifugal rotary machine further comprises a plurality of return vanes which are provided in the guiding flow path guiding the working fluid in at least one impeller from among the impellers provided in the plurality of stages and which are provided at intervals in a circumferential direction around the axis, and

wherein in each return vane, a trailing edge positioned on the inside in the radial direction is formed such that a second end portion on the second side in the axial direction is positioned closer to the inside in the radial direction than a first end portion on the first side in the axial direction.

2. The centrifugal rotary machine according to claim 1 ,

wherein each return vane is formed such that a length along a flow direction of the working fluid on the second side in the axial direction is longer than that on a length along a flow direction on the first side in the axial direction.

3. The centrifugal rotary machine according to claim 1 ,

wherein the trailing edge of each return vane gradually extends to the inside in the radial direction from the first end portion toward the second end portion.

4. The centrifugal rotary machine according to claim 1 ,

wherein the trailing edge of each return vane is curvedly formed to be convex toward the inside in the radial direction or to be concave toward the outside in the radial direction between the first end portion and the second end portion.

5. The centrifugal rotary machine according to claim 1 ,

wherein in the trailing edge of each return vane, the second end portion is positioned closer to the inside in the radial direction than a normal line extending perpendicularly to an upstream wall surface on the first side in the axial direction in the guiding flow path from the first end portion.

6. The centrifugal rotary machine according to claim 1 ,

wherein in each return vane, a leading edge positioned on the outside in the radial direction is linearly formed along the axis.

7. The centrifugal rotary machine according to claim 1 ,

wherein in each return vane, an axial length of the trailing edge is longer than that of the leading edge positioned on the outside in the radial direction.

8. The centrifugal rotary machine according to claim 2 ,

wherein the trailing edge of each return vane gradually extends to the inside in the radial direction from the first end portion toward the second end portion.

9. The centrifugal rotary machine according to claim 2 ,

wherein the trailing edge of each return vane is curvedly formed to be convex toward the inside in the radial direction or to be concave toward the outside in the radial direction between the first end portion and the second end portion.

10. The centrifugal rotary machine according to claim 2 ,

wherein in the trailing edge of each return vane, the second end portion is positioned closer to the inside in the radial direction than a normal line extending perpendicularly to an upstream wall surface on the first side in the axial direction in the guiding flow path from the first end portion.

11. The centrifugal rotary machine according to claim 3 ,

wherein in the trailing edge of each return vane, the second end portion is positioned closer to the inside in the radial direction than a normal line extending perpendicularly to an upstream wall surface on the first side in the axial direction in the guiding flow path from the first end portion.

12. The centrifugal rotary machine according to claim 4 ,

wherein in the trailing edge of each return vane, the second end portion is positioned closer to the inside in the radial direction than a normal line extending perpendicularly to an upstream wall surface on the first side in the axial direction in the guiding flow path from the first end portion.

13. The centrifugal rotary machine according to claim 2 ,

wherein in each return vane, a leading edge positioned on the outside in the radial direction is linearly formed along the axis.

14. The centrifugal rotary machine according to claim 3 ,

wherein in each return vane, a leading edge positioned on the outside in the radial direction is linearly formed along the axis.

15. The centrifugal rotary machine according to claim 4 ,

wherein in each return vane, a leading edge positioned on the outside in the radial direction is linearly formed along the axis.

16. The centrifugal rotary machine according to claim 2 ,

wherein in each return vane, an axial length of the trailing edge is longer than that of the leading edge positioned on the outside in the radial direction.

17. The centrifugal rotary machine according to claim 3 ,

wherein in each return vane, an axial length of the trailing edge is longer than that of the leading edge positioned on the outside in the radial direction.

18. The centrifugal rotary machine according to claim 4 ,

wherein in each return vane, an axial length of the trailing edge is longer than that of the leading edge positioned on the outside in the radial direction.