Preliminary Numerical Validation of the Frequency Response Method on the Study of Aero-Damping in a Linear Oscillating Compressor Cascade

Abstract

Preliminary numerical simulations are performed for validation of using the frequency response method on the study of aero-damping in a linear oscillating compressor cascade. The traveling wave method and influence coefficient method, based on the idea of the energy method, are also adopted for reference and comparison. The linearity of the unsteady pressure and the finite propagation of small flow disturbance is verified. The results of the aero-damping ratio obtained from different methods are in good agreement. Qualitative analysis is made on how the unsteady aerodynamic pressure distribution determines the overall aero-damping. When the frequency sweeps are conducted to measure aero-damping, the influence of aerodynamic stiffness cannot be ignored and the natural frequency offset caused by it should be taken into account. The existence of the two sidewalls in cascade has a certain impact on the measurement results, but it is still in an acceptable range. The application of the frequency response method on the study of aero-damping in the experiment is proved to be feasible and reliable in principle by numerical simulation.