Centrifugal compressor

A centrifugal compressor, comprising:

• a housing including an intake-air inlet which opens in a direction of a rotational axis of the centrifugal compressor, and an intake-air channel which connects to the intake-air inlet;
• an impeller wheel disposed inside the housing rotatably around the rotational axis, and configured to compress intake gas which flows in from the intake-air inlet;
• and
• a swirl-flow generating unit disposed between the intake-air inlet and the impeller wheel inside the housing and configured to swirl the intake gas which flows in from the intake-air inlet,
• wherein the swirl-flow generating unit includes:
• a swirl-flow generating part which includes a plurality of guide vanes disposed in a circumferential direction along an inner circumferential wall of the housing and which is configured to swirl the intake gas flowing in from the intake-air inlet around the rotational axis by means of the plurality of guide vanes;
• and
• a central intake-air flow part which is a space surrounded by the swirl-flow generating part and which opens in the direction of the rotational axis so that the intake gas flowing in from the intake-air inlet passes through the central intake-air flow part,
• wherein the housing includes a recirculation flow path which is disposed on an outer side of the intake-air channel and which brings an outer circumferential section of the impeller wheel into communication with the intake-air channel at an upstream side with respect to the impeller wheel,
• wherein an opening end portion at an upstream side of the recirculation flow path is disposed upstream with respect to the swirl-flow generating unit, and return flow air from the opening end portion at the upstream side of the recirculation flow path flows toward the guide vanes of the swirl-flow generating part,
• wherein the housing is divided into an upstream housing and a downstream housing at a position where the recirculation flow path is divided,
• wherein the swirl-flow generating unit includes an outer cylindrical member to be fitted to the inner circumferential wall of the housing and the guide vanes arranged in a circumferential direction along an inner circumferential wall of the outer cylindrical member, the swirl-flow generating unit being formed as a separate body from the housing, and
• wherein the outer cylindrical member is fitted to an inner circumferential wall of the upstream housing.