An experimental investigation of active and passive control of rotating stall in axial compressors

Presents results to date from on-going analytical and experimental investigations of passive and active control methods for suppression of stall in axial flow compressors, The passive control method involved inclusion of flow separators in the inlet and outlet ducts of the compressor. The active control methods investigated included bleed valve modulations, flow recirculation from plenum bleed to inlet of the compressor and fuel flow modulations. It was found that in contrast to theoretical expectations, the use of separators in the inlet and/or outlet ducts did not prevent the onset of rotating stall. However, it was found that with proper number of separators, the onset manner of the rotating stall was tempered. Experimental results to date indicate that it is possible to significantly suppress the onset of rotating stall through a combination of passive and active control schemes, and thus, extend the useful operational range of a compressor.