Abstract: An inlet guide vane apparatus for the adjustable insertion and retraction of a guide vane into the inlet passage of a compressor and the adjustable varying of the flow direction of the fluid downstream of the vane body by varying the angle of attack of the vane body includes a longitudinal vane body protruding part way across the inlet passage of the compressor through an aperture in the inlet shroud, and a winglet attached to the end of the vane body extending inboard the compressor inlet shroud. The degree of insertion of the vane body into the passage may be controlled by a pneumatically actuated slidable plunger attached to the vane body and responsive to the compressor discharge pressure. The angle of attack of the vane body may be controlled by a rotatable plunger cylinder having a longitudinally extending groove engaging a pin radially extending from a lateral portion of the body of the plunger.

Abstract: Acoustically sized bleed passages are provided in the shroud wall of a rotary compressor to admit expansion waves to the suction-sides of successive passing blades to control the boundary layer. The expansion waves are generated by reflecting compression waves formed in the passages by the pressure sides of passing blades. The passages are oriented to receive high pressure bleed gas at maximum gas particle velocity, and the passages are configured to diffuse the gas to increase static bleed pressure.