To miniaturize a centrifugal turbo machine while sufficiently lowering the fluid loss.
A side plate 12 is provided with a half-open passage 15 for turning the flow from the nearly centrifugal direction to the nearly axial direction and while leading the fluid to a return flow passage in a part facing to an enlarged passage 14 pinched between a diffuser vane 13a and the adjacent diffuser vane 13b at a part close to the outlet side than a rear edge 13a10 of a negative pressure surface 13a1 of the diffuser vane 13a. Each diffuser vane 13a, 13b, 13c... is formed so that thickness of a part 13a20, 13b20, 13c20... of parts facing to the half-open passage 15 among pressure surfaces 13a2, 13b2, 13c2... are gradually reduced like a taper-shape toward the downstream in the axial direction.
TANAKA TEIJI
NISHI RYUICHI
UEYAMA TOSHIHARU
NAGAI YUJI
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