AXIAL COMPRESSOR PERFORMANCE DURING SURGE

There is limited information available in the literature about flow co nditions in axial compressors during surge. This article presents deta iled measurements from a low-speed test rig instrumented to pick up de tails 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 diff erences in cycle behavior between ''classic surge'' and ''deep surge'' are investigated, and it is shown that the shape of the compressor ch aracteristic determines which of these will occur. From the results it is also concluded that some important factors, such as overall pressu re rise and size of hysteresis loop, have not received sufficient atte ntion in existing techniques for predicting the rotating stall/surge b oundary. In line with these findings an Appendix by E. M. Greitzer pre sents a more general version of the ''B Parameter,'' which takes into account the influence of compressor design variables on the stalling b ehavior of the compressor.