AXIAL COMPRESSOR PERFORMANCE DURING SURGE

There is limited information available in the literature about flow conditions in axial compressors during surge. This article presents detailed measurements from a low-speed test rig instrumented to pick up details Of axial and circumferential flow disturbances. The results show that surge is initiated by rotating stall, and that the ensuing surge cycle is a sequence of well ordered cause-and-effect events. The differences in cycle behavior between ''classic surge'' and ''deep surge'' are investigated, and it is shown that the shape of the compressor characteristic determines which of these will occur. From the results it is also concluded that some important factors, such as overall pressure rise and size of hysteresis loop, have not received sufficient attention in existing techniques for predicting the rotating stall/surge boundary. In line with these findings an Appendix by E. M. Greitzer presents a more general version of the ''B Parameter,'' which takes into account the influence of compressor design variables on the stalling behavior of the compressor.