To provide a mixed flow compressor with a screw improved in suction performance and balance especially and applicable to a comparatively small gas turbine as a compressor used for a dispersion type power generator, an automobile engine, or a propeller for a ship.
This compressor is constructed of a casing 5 arranged in the circumference part of an impeller 3, a suction casing 6 connected to the front end of the casing 5 and sucking gas in the axial center direction, and a diffuser 7 leading gas compressed by rotation of the impeller 3 in the mixed flow direction. In this compressor, a plurality of spiral vanes 9 wound on a conical hub 1 into a screw shape are fixed, while the outer circumferential tip parts 9a on the initial end side of the spiral vanes 9 are projected toward the suction casing 6, and the inner circumferential part of a suction port for the spiral vanes 9 is spread widely for guiding inflow of the gas in the tip part of the suction port, so that a suction air amount is increased. Consequently, suction performance and volume efficiency is improved and a compressing pressure on the gas flowing between the spiral vanes 9 can be increased continuously, and local separation of the compressed air can be prevented and vibration and noise due to surging can be eliminated.