Validation and Analysis of Nonlinear System of Centrifugal Compressor using Hot Wire Flow Measurement and Jacobian Matrix

A mathematical method is developed to predict surge and instability inception in a centrifugal compressor map based on Greitzer and Moore model. The method uses phase plane and Jacobian matrix to determine stable and unstable zone of centrifugal compressor and to extract limit cycle in unstable zone. In order to evaluate accuracy of analytical method, a compressor test rig facility is designed and tested in order to be compared with theoretical results. Accurate Honeywell piezoelectric pressure transducers are used to measure time averaged pressure at inlet and outlet ducts of the compressor. In order to record the flow fluctuation precisely, hot wire sensors are installed in entrance and exit of impeller. The results represent instability inception near true stall point but different from measured data. The discrepancy mostly originates from inlet and outlet ducts which causes measure stall point of compressor deviates from true one. An analytical method which is able to predict surge and instability in a compressor is highly significant for instrumentation and controlling of system.