Pipe diffuser with aerodynamically variable throat area

Claim 1

A compressor assembly comprising: a rotatable bladed impeller having an annular discharge region; an annular diffuser housing surrounding the discharge of said impeller, said diffuser having a plurality of generally conically diverging tangentially directed diffuser passages having throats which intersect adjacent the discharge of said impeller to form a series of generally scalloped inlet edges to said diffuser passage throats, said diffuser passages having an angle of incidence with respect to the air leaving the discharge region of said impeller that directs the air more radially outward than a free vortex flow, thereby creating high and low pressure regions on opposite sides of said scalloped inlet edges; and means for injecting air into the throats of said diffuser passages and means for supplying a source of air adjacent said throats at a static pressure level higher than that of the air in the throats of said passages, and means for forming ports from said source of pressurized air for injection into the throats of said diffuser passages to aerodynamically alter the flow characteristics of said throats and means including ports for injecting air to the low pressure side of said scalloped inlet edges thereby aerodynamically reducing the effectivE incidence of the passages relative to the flow from the impeller.