Variable geometry diffuser assembly

Claim 1

In a gas turbine engine having in flow series arrangement a compressor having a variable geometry diffuser, and a hot section including a combustor and a turbine, wherein said turbine is coupled to said compressor via a shaft, said compressor comprising: a radial impeller mounted on said shaft and having an air inlet and an air outlet; a housing including a first annular wall, having a front and back surface, circumscribing said impeller and a second annular wall having a front and back surface spaced apart from said first wall, said front surface of said first wall facing said front surface of said second wall and defining therebetween a diffuser passageway downstream of said impeller and in fluid communication with said air outlet, each of said front surfaces having a plurality of circumferentially disposed circular recesses positioned so that each recess on said front surface of said first wall aligns with one of said recesses on said front surface of said second wall, each of said recesses on said first wall opening into a bore that extends through said first wall, said first and second walls positioned within said gas turbine engine so that said only said back surface of said second wall is exposed to said hot section; a plurality of circumferentially spaced diffuser vanes, each extending from a leading edge to a trailing edge and having disposed therebetween, a pressure side portion, a suction side portion and a first and second endwall, said endwalls being substantially perpendicular to said suction side portion and said pressure side portion, a first disk member attached to said first endwall and rotatably received in one of said recesses in said first wall, and a second disk member attached to said second endwall and rotatably received in one of said recesses in said second wall, said diffuser vanes disposed in said diffuser passageway so that said leading edges face said air outlet and said endwalls face said annular walls, a plurality of shafts each secured at a first end to one of said first disks and mounted for rotation in one of said bores and extending therethrough; a unison ring mounted for rotation on said back surface of said first annular wall; and a plurality of arm members, each of said arm members secured for rotation at a first end to said unison ring and secured at a second end to one of said shafts, whereby in response to the rotation of said unison ring, each of said arms, shafts, and vanes are simultaneously rotated.