An object is to provide an air intake duct structure for a centrifugal fluid machine, capable of swirling the fluid introduced into the impeller in the reverse direction to increase the pressure ratio when the flow rate is high and swirling the fluid in th...

A vent duct (1) having an inner fluid flow passage includes a bent portion (11) formed to a duct body portion at which the fluid flow passage is bent, and a protruded portion (20) formed on a downstream side of the bent portion (11) so as to protrude from ...

An air-intake manifold includes a plurality of air-intake pipes connecting between a collector and an air-intake pipe mount. Each air-intake pipe 3 is bent to have a predetermined shape. Each air-intake pipe 3 is fabricated by bending a substantially strai...