To provide a turbo fluid machine controlling noise generated due to interference of grooves on a casing inner circumference surface for stabling head-discharge characteristics and impeller blades.
A plurality of grooves 4 are formed on the inner circumference surface of the roughly cylindrical casing 2 from an inlet side of the blades to an existing area of the blades in a pressure gradient direction of operation fluid to eliminate an increasing tendency of the head-discharge characteristics. The casing 2 is provided with a casing liner 5 and a communication hole 8 together with the plurality of grooves is formed on an inner circumference surface of the casing liner. Consequently, a resonance type silencer (header tank chamber 9) connected to a position close to a position where the grooves 4 and the blades of the impeller 1 oppose is constructed. A dominant frequency of the resonance type silencer is set corresponding to noise caused by interference between the grooves and the blades by suitably setting volume thereof to surely reduce the noise.
SUDO SUMIO
IRIE KOICHI
