FLOW CONTROL METHOD AND MEANS

The method controls gas flow in an axial flow compressor in which the flow at one or more chosen station in the direction of flow through the compressor is sensed at a series of circumferentially spaced positions. Flow variations above a predetermined limit are evaluated to initiate a response if a disturbance above a predetermined acceptable level is detected. When such a disturbance is detected, higher pressure gas bled from downstream is injected at a station to supplement the main gas flow. An incipient rotating stall cell will appear as a variation occurring sequentially at the circumferentially spaced positions. By responding to such a condition with a pressure injection, it is found possible to suppress both rotating stall and surge conditions in the compressor before this disturbance develops fully. The same method can be arranged to counter steady state distortion.