基于LBM-LES方法翼型纯音噪声数值研究

Numerical study of airfoil tonal noise based on LBM-LES

基于LBM-LES方法,对中低雷诺数下的NACA0012翼型纯音噪声进行了直接计算,研究了不同迎角和雷诺数对纯音噪声的影响。计算结果表明,翼型的声源主要位于翼型的分离区和后缘处,在不同迎角和雷诺数下的声辐射特征均具有偶极子声场的特点;迎角的增大将引起较大的旋涡尺度和湍流强度,吸力面声源区域前移。声压级频谱分析表明,随着迎角的增大,纯音噪声逐渐消失,噪声谱最终呈现宽频特征;随着雷诺数的增大,后缘压力脉动增大。声压级频谱中,主频频率随着雷诺数的增大而增大,且符合Paterson公式的幂律关系。此外,声压级频谱特性随着雷诺数的增大表现出由离散特性向宽频特性转变的趋势。

Based on the LBM-LES method,the direct calculation of NACA0012 airfoil tonal noise at moderate and low Reynolds numbers are performed.The effects of different angles of attack and Reynolds numbers on tone noise were studied.The computation results indicate that the acoustic source of the airfoil is mainly located at the separation zone and the trailing edge of the airfoil.The acoustic radiation characteristics at different angles of attack and Reynolds number have the characteristics of the dipole acoustic field.The increase of the angle of attack will enlarge vortexes and raise turbulence intensity,and the acoustic source area of the suction surface will move forward.The sound pressure level spectrum analysis shows that the tonal noise gradually disappears and the noise spectrum finally becomes broadband as the angle of attack increases.As the Reynolds number increases,the trailing edge pressure pulsation increases.The primary frequency in the sound pressure level spectrum increases with the increase of the Reynolds number,and conforms to the power law relationship of the Paterson formula.In addition,the spectral characteristics of the sound pressure level show a tendency to change from discrete to broadband as the Reynolds number increases.