Efficient numerical prediction of blade forced response under inlet distortion

Abstract

The compressor blade in an aircraft gas turbine engine may suffer from forced vibration problems under the unsteady aerodynamic force due to inlet distortion. This paper develops an efficient numerical method combination to predict the forced response. The computational fluid dynamics (CFD) method is combined with the Fourier transform method to simulate the unsteady flow field under inlet distortion. Then, the forced response of the blade is obtained by the frequency-domain method based on the modal force. The results show that the developed method combination improves the unsteady flow calculation efficiency by 20 times and the response calculation efficiency by 48 times at the cost of less than 5% accuracy compared with the traditional method combination, including the unsteady flow field calculation method based on the three-row full-annulus model and the transient analysis method for calculating the forced response. Finally, the developed method combination is used to analyze the forced response of the blade under different inlet total pressure distributions. The results indicate that the forced response can be effectively decreased by decreasing the total pressure difference and increasing the sector angle difference between the high-pressure and low-pressure areas.