Analysis of Stall Onset in a Multistage Axial Flow Compressor in Response to Engine Icing

Abstract

Propulsion system instabilities such as compressor surge and stall can arise due to ice ingested by an aircraft engine flying through high ice water content regions. Performance and operability are affected by ice ingestion into a gas turbine engine compression system. Since the 1980's ingestion of ice particles into engines have caused over one hundred engine power loss events. This paper presents an analysis of a multistage compressor system response to ice ingestion. Towards this, an aero-thermodynamic model of the discrete particles that captures mass and heat balances with air, is constructed. The computational methodology integrates it with a quasi-one-dimensional unsteady flow model with additional source terms from the discrete phase. From numerical simulations of the coupled continuous-discrete phase flow model, it is observed that a re-matching of the stages across the compressor occurs with increasing ice flow rates to accommodate loss of energy to the ice flow. The axial flow and pressure oscillations with increasing ice flow rates results in an eventual irretrievable unsteady compressor operating point excursion to stall side. The flow solver simulates the onset of a surge-stall event and identifies the stalling stage of the compressor. The numerical simulations correlate the magnitude of ice flow rates to pressure disturbances ultimately causing compressor instability.