基于非定常流场的离心风机气动噪声分析

Analysis of the Aeroacoustics in Centrifugal Fan Based on Numerical Simulation of Unsteady Viscous Flow

提出了一种不直接求解声场却能为离心风机降噪提供有用信息的分析方法.首先,利用有限容积法对风机内部的非定常流场进行计算.然后,采用时域和频域分析方法对流场内静压脉动的强度和频率进行分析.最后,根据声学基本理论,判定风机内部主要气动噪声源的位置及噪声类型.应用该方法对某离心风机进行了计算,并将分析计算结果与该风机的噪声测量结果进行了对比,证明该方法能够有效地判断气动噪声源的位置和噪声类型.

A new method was proposed to analyse the intensity and location of dominant aerodynamic noise source and the type of the noise in a centrifugal fan. In this method, the numerical solution of aeroacoustic field was avoided because of the difficulties of solving the Green function in an irregular space. To find the noise source, the three-dimensional unsteady viscous flow in the centrifugal fan was calculated by applying finite volume method and high order discrete scheme. Then, the time-domain and frequency-domain analyses on fluctuating component of static pressure in the flow field were carried out. Based on these numerical results, the intensity and location of dominant aerodynamic noise source and the type of the noise were ascertained according to the acoustic principles and the characteristics of the sound propagation. The present method was applied to an industrial centritfugal fan with forward-curved blades. And the numerical results were compared with our experimental data for the same machine. It is concluded that this method could contribute significantly to indicating the sound generation mechanisms inside centrifugal fans and be valuable for noise reduction of the fans.