基于无限元方法预报非均匀流中螺旋桨的流噪声

Prediction of Flow Noise of Propeller in Non-Uniform Flow Based on Acoustic Infinite Element Method

为了系统地研究非均匀流场中螺旋桨流噪声的特点,采用CFD与声学无限元方法结合的方式,对螺旋桨的频域噪声进行数值预报。通过采用大涡模拟方法对非均匀流场中的螺旋桨水动力性能进行计算,然后运用ACTRAN软件的声学无限元方法,对螺旋桨的无空泡噪声进行数值模拟,并对特征点进行频域分析。流场计算结果显示:非定常计算得到的螺旋桨水动力系数与试验值吻合良好,LES模拟得到的流场初值是可信的;通过分析噪声分布云图及特征点频谱曲线得出:非均匀流场中螺旋桨的辐射噪声主要集中在低频段,且该频段的噪声主要由偶极子组成,同时噪声衰减速度随频率增大而减小,螺旋桨轴向声压级高于径向两侧,验证了计算结果的可靠性,为螺旋桨的水下噪声预报提供了一种新的方法。

Hydrodynamic performance in non-uniform flow field is simulated with large eddy simulation. Software ACRTAN is applied to simulate non-cavitating propeller noise, while noise of feature point is analyzed in frequency-domain. Hydrodynamic coefficients of propeller under unsteady simulation condition coincide closely with test results, and the reliability of initial value from LES simulation is verified. Noise contours and spectrum curve of feature points show that the propeller radiated noise in non-uniform flow field is distributed mainly in low frequency-domain and noises are mainly dipoles. Noise attenuation rate decreases with the increase of frequency. Propeller axial SPL is bigger than that at radial sides. Reliability of the simulation is verified in both qualitative and quantitative aspects.