Method of vibration diagnostics of aerodynamic and aeroelastic oscillations in gas turbine engine compressor

Abstract

The paper analyzes aeroelastic (flutter) and aerodynamic (rotating stall) oscillations in gas turbine engine compressors. We review the external factors that influence these oscillations. We propose a new method of diagnosing hazardous oscillations. The method is based on the analysis of frequency characteristics. The novelty of the method is elements of forecasting introduced in it. We infer the presence of dangerous oscillations by a certain threshold level of the amplitude of the dynamic signal. We forecast this threshold depending on the operation conditions of a gas turbine engine. If the amplitude of the signal reaches the threshold level the engine speed is decreased by changing the rate of fuel consumption. This measure prevents an emergency. The method was implemented during bench tests of an aircraft gas turbine engine.