Stalled flow performance for axial compressors. I - Axisymmetric characteristic

A study of stalled flow performance of multistage compressors is presented. A new compressor characteristics is developed, describing the axisymmetric pumping performance over the entire compressor flow range, including reversed flow. This axisymmetric characteristic is required in any current rotating stall model. It is possible for the axisymmetric performance to rise above the measured stall point pressure rise, thus indicating greater unstalled pressure rise potential. In this context, the axisymmetric characteristic in forward flow is viewed as paralleling diffuser performance. A simple two-dimensional reversed flow model is presented, and is shown to be in reasonable agreement with available high backflow compressor data. The model predicts that the blade stagger angle greatly influences the reversed flow characteristics. Calculations are carried out using the rotating stall model of Moore and the axisymmetric characteristic developed herein, and a technique is suggested for estimating the axisymmetric curve over the entire flow range.