Patent ID: 6488469
Filing Date: 2002-12-03
Classification: F02C,F04D,F05D,Y02T

Abstract:
A gas compressor having two stages comprising:a mixed flow stage with a mixed rotor rotatable about a compressor axis having a circumferential array of mixed flow blades between a mixed flow hub and an associated mixed flow shroud, wherein the mixed stage has: a gas outlet absolute velocity in the operating range of 0.75 to 0.99 Mach; and a compression ratio in the range of 2.5-2.9; a centrifugal stage with a centrifugal rotor rotatable about the compressor axis and downstream of the mixed rotor, the centrifugal rotor having a circumferential array of radially extending centrifugal flow blades between a centrifugal flow hub and an associated centrifugal flow shroud, wherein the centrifugal stage has: a gas inlet absolute velocity in the operating range of 0.30 to 0.60 Mach; and a compression ratio in the range of 4.0-4.5; and an intermediate duct having: an inner duct wall defining an axially curvilinear transition surface of revolution between an outlet end of the mixed flow hub and an inlet end of the centrifugal flow hub; and an outer duct wall defining an axially curvilinear transition surface of revolution between the outlet end of the mixed flow shroud and the inlet end of the centrifugal flow shroud.