Variable geometry centrifugal compressor diffuser

Claim 1

A variable geometry centrifugal compressor diffuser comprising a housing having spaced parallel walls extending laterally of a central axis, a plurality of fixed radially and circumferentially extending relatively thin vane segments disposed in a circumferentially spaced array in sealed relation to said walls, the circumferential spacing between a radially inner extremity of each of said fixed segments defining a fixed throat area, a plurality of radially and circumferentially movable vane segments of relatively thin radially outwardly divergent wedge-shaped radial cross section abutting said fixed segments, respectively, each of said movable vane segments having a radially inner extremity movable between a first position radially inwardly of the radially inward extremity of said fixed vane segments and a second position radially outwardly of the inner extremity of said fixed vane segments, a movable throat area between a radially inward extremity of each of said fixed vane segments and an opposed circumferentially, spaced movable vane segment being less than said fixed throat area when said movable segments are in said first position and equal to said fixed throat area when said movable segments are in said second position, an inlet angle between the adjacent fixed or movable vane segments being relatively constant at all positions of said movable vane segments whereby diffuser throat area is variable substantially independently of inlet angle.