Method for Predicting Unsteady Vibration of Gas Turbine Compressor Blades Under Subsonic Near-Stall Conditions

Abstract

Wind tunnel tests and numerical calculations using computational fluid dynamics (CFD) analysis and structural finite element analysis were conducted to clarify the vibration characteristics of gas turbine compressor blades under subsonic near-stall conditions. The results show that discrete low-frequency components of pressure are created by variation of the separation region and that discrete high-frequency components are created by vortex shedding when the compressor blade incidence angle is in the stall region. The natural frequency component resonated by the random fluid force is dominant in blade vibration. The numerically calculated phenomena agree well with the measured phenomena. The vibration amplitude increases with the incidence angle and the Mach number, and it increases rapidly at higher angles. A simple method for predicting the vibration stress using static calculations is reasonably accurate.