Turbine

A turbine that rotates an impeller by energy of a fluid, the turbine comprising:

• an impeller chamber housing the impeller and comprising an inflow portion of the fluid and an outflow portion, from which the fluid flows out in an outflow direction substantially parallel to an axis of the impeller;
• a bypass flow passage bypassing an inside of the impeller chamber;
• an outer duct having an inner peripheral surface that is substantially conical and expands in diameter in the outflow direction from the outflow portion;
• and
• an inner duct disposed on an inner side of the outer duct and being tubular and extending in the outflow direction from the outflow portion,
• wherein a diffuser flow passage that expands in diameter in the outflow direction is disposed in the inner duct at least in a portion between the outflow portion and a distal end portion of the inner duct, and
• an outlet of the bypass flow passage and a waste gate valve that opens and closes the outlet are disposed on the inner peripheral surface,
• wherein an outer flange that extends in a radial direction of the impeller is disposed on a distal end portion of the outer duct,
• an inner flange disposed on the distal end portion of the inner duct, wherein the inner flange extends in the radial direction of the impeller and has one or more through holes, and
• the inner flange is fixed to the outer flange.