Centrifugal compressor

A centrifugal compressor comprising:

• a compressor housing accommodating an impeller;
• and
• a casing treatment,
• wherein
• the compressor housing includes:
• an air introduction hole through which air is introduced toward the impeller;
• an annular portion disposed inside the air introduction hole;
• and
• spoke portions, each of the spoke portions connecting an inner circumferential wall surface of the air introduction hole and the annular portion,
• the casing treatment includes:
• a tubular portion provided on an upstream side of the annular portion in the air introduction hole in an introduction direction of the air;
• and
• wing-like portions, each of the wing-like portions extending from the tubular portion toward a downstream side in the introduction direction of the air;
• in the casing treatment, an inside of the tubular portion forms a main flow path of the air, and the wing-like portion engages with the annular portion to form a sub flow path,
• the sub flow path branches from the main flow path and joins the main flow path again together with the annular portion and the spoke portion,
• the number of the spoke portions is equal to the number of the wing-like portions, and
• the spoke portions and the wing-like portions are arranged at same positions in a circumferential direction of the annular portion, respectively.