Experimental Investigations of Micro Air Injection to Control Rotating Stall

Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be aneffective method to delay the inception of rotating stall in a low speed axial compressor.Considering the practicalapplication a new type of micro injector was designed and described in this paper,which was imbedded in thecasing and could be moved along the chord.In order to verify its feasibility to other cases,such as high subsonicaxial compressor or centrifugal compressor,some other cases have been studied.Experimental results of the samelow speed axial compressor showed that the new injector could possess many other advantages besides success-fully stabilizing the compressor.Experiments performed on a high subsonic axial compressor confirmed the ef-fectiveness of micro air injection when the relative velocity at the blade tip is high subsonic.Meanwhile in orderto explore its feasibility in centrifugal compressor,a similar micro injector was designed and tested on a lowspeed centrifugal compressor with vaned diffuser.The injected mass flow was a bit larger than that used in axialcompressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugalcompressor.

Experimental investigations of micro air injection to control rotating stall

Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor.Considering the practical application a new type of micro injector was designed and described in this paper,which was imbedded in the casing and could be moved along the chord.In order to verify its feasibility to other cases,such as high subsonic axial compressor or centrifugal compressor,some other cases have been studied.Experimental results of the same low speed axial compressor showed that the new injector could possess many other advantages besides success- fully stabilizing the compressor.Experiments performed on a high subsonic axial compressor confirmed the ef- fectiveness of micro air injection when the relative velocity at the blade tip is high subsonic.Meanwhile in order to explore its feasibility in centrifugal compressor,a similar micro injector was designed and tested on a low speed centrifugal compressor with vaned diffuser.The injected mass flow was a bit larger than that used in axial compressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugal compressor.