Research on Accuracy of Flowing Field Based on Numerical Simulation for Tonal Noise Prediction in Axial Compressor

Abstract

For the predicting of compressor noise, Lighthill analogy method based on numerical simulation has usually been adopted. Therefore, accuracy of the numerical simulation of the flowing filed is very important to the noise estimation. In this paper, nonlinear harmonic (NLH) method, which is one of promising numerical simulation methods used for the noise prediction, is compared with dual time step (DTS) method based on the calculating of the flowing field of one and a half stage compressor. It is found that the time consumption of NLH is actually decreased by about 70% compared with DTS. All the same, pressure fluctuation in the results obtained from NLH is more obvious than that of DTS in the upstream channel and downstream channel. Meanwhile, the two series of numerical simulation results are compared respectively with experiment data measured by dynamic pressure sensors. It is observed that the results from DTS is much closer to experimental data in both time domain and frequency domain. It is believed that the overmuch fluctuation found in NLH method is mainly caused by the contradiction between actual flowing pattern and periodical assumption made by NLH method initially. In addition, the pressure distribution around rotor blade surface, which is one of important tonal noise sources, is studied in detail as well.