13th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Complex flow fields arise during the reverse flow phase of compressor mild surge cycles, yielding potentially increased flutter risks. Variable nozzle models enable to simulate entire surge cycles and to evaluate the blade flutter stability at reverse flow conditions. Nevertheless, the accuracy of the simulation results strongly depends on the correct selection of the model parameters. Former studies have shown the influence of the surge volume on the compressor global unsteady behavior. The current study focuses on the impact of the nozzle throttle area on the compressor surge behavior and demonstrates that this parameter has to be considered additionally to achieve accurate results with this modelling approach. A conceptual model consisting of one passage of a single rotor row is used to identify the basic system behavior and to determine the influence of the model parameters.