Centrifugal compressor and turbocharger

A centrifugal compressor configured to compress a fluid by using a centrifugal force, comprising:

• a housing provided with a shroud therein;
• a wheel rotatably provided in the housing;
• an introduction flow passage provided on an inlet side of the wheel in the housing, and introduces the fluid into the housing;
• an annular diffuser provided on an outlet side of the wheel in the housing;
• an annular throttle portion provided between the wheel and the diffuser to communicate with the diffuser, the throttle portion including a flow passage width gradually reduced along a flowing direction of a main flow;
• a scroll having a spiral shape, provided on an outlet side of the diffuser to communicate with the diffuser;
• a discharge flow passage provided to communicate with a winding end side of the scroll, the discharge flow passage configured to discharge the fluid to an outside of the housing;
• and
• a tongue portion separating the discharge flow passage and a winding start side of the scroll, wherein
• a flow passage length of the diffuser in a radial direction of the wheel increases from a first area to a second area, the first area being located on the winding start side of the scroll, the second area being located on an opposite side to the first area across a shaft center of the wheel and being located closer to the winding end side than the first area, and
• an outer peripheral edge of the diffuser is positioned concentrically with the wheel.