Diffuser including movable vanes

Claim 1

An annular diffuser for use with a centrifugal compressor having a radial flow impeller whose outer periphery is closely surrounded by the inner circumference of the annular diffuser, said diffuser comprising: a forward annular end plate; a rear annular end plate axially spaced from said forward annular end plate; a plurality of pivotable vanes positioned between said end plates, said vanes and said end plates defining a plurality of channels, the centerlines of said channels being tangent to a circle having approximately the same diameter as said impeller, the innermost end of each of said vanes comprising a wedge having a taper chosen such that adjacent vane members, when abutted by said forward and rear end plates, form a channel therebetween having constant cross-sectional dimensions over a length defined as being between adjacent wedge-shaped inner portions of said vanes, the wedge-shaped innermost end of each of said vanes being followed by an oppositely tapered outer end whereby a multiplicity of said vanes when assembled in substantially radial formation between said end plates form an expanding volume diffuser; and pivoting means for simultaneously pivoting each of said vanes to vary the cross-sectional area of said channels.