On-off valve device and rotary machine

A rotary machine, comprising:

• a rotary shaft which rotates about an axis;
• a turbine rotor blade which rotates along with the rotary shaft;
• a housing which covers the rotary shaft and the turbine rotor blade;
• and
• an on-off valve device disposed in the housing,
• wherein a scroll flow path is spirally formed continuing to an inflow port of the housing and has a flow path area gradually decreased toward a downstream side of a fluid flow,
• a suction flow path is formed to lead from the inflow port to the scroll flow path and the suction flow path is formed between a first wall surface of the housing and a second wall surface of the housing that faces the first wall surface,
• the on-off valve device includes a valve body which is configured of a single piece or multiple divided pieces and is disposed in the suction flow path,
• the valve body extends from the upstream side toward the downstream side of the fluid flow, and the valve body is rotatably configured in the housing in a direction toward and away from the first wall surface and the second wall surface,
• the valve body is configured to have a first surface which faces the first wall surface and gradually goes away from the first wall surface after gradually approaching the first wall surface from the upstream side toward the downstream side of the fluid flow, and a second surface which faces the second wall surface, and
• an upstream-side narrowed flow path is formed between the first wall surface and the valve body at an end on the upstream side, and a downstream-side narrowed flow path is formed between the second wall surface and the valve body at an end on the downstream side,
• wherein the rotary machine further includes multiple guide portions which are disposed in the scroll flow path to go away from each other in a circumferential direction of the rotary shaft, disposed on the outside in a radial direction of the rotary shaft from the turbine rotor blade, and includes curved guide surfaces facing inwardly in the radial direction, and
• each of the guide surfaces in the guide portions positioned on the upstream side in the fluid flow is provided so as to guide the fluid toward the next guide surface in the guide portion positioned on the downstream side.