翼型湍流尾缘噪声半经验预测公式改进

改进了传统的翼型湍流边界层尾缘噪声BPM半经验预测公式。传统的BPM半经验湍流边界层尾缘噪声预测公式对高攻角和厚翼型在高频范围的预测结果大于实验结果,通过分析比较传统BPM半经验预测公式和Howe翼型尾缘噪声理论模型发现:这主要是由于传统BPM半经验预测公式对压力面声源噪声辐射高估引起的。因此将压力面声源噪声辐射与吸力面声源噪声辐射的幅值比由原来的边界层位移厚度一次方比值改进为二次方比值,进而得到了改进后的BPM半经验预测公式;使用改进后的BPM半经验预测公式对NACA0012翼型在不同来流不同攻角下的噪声辐射进行了预测比较,发现对于NACA0012翼型,改进后的BPM半经验预测公式具有较高精度;另外也预测了较厚的风力机翼型DU-96-W-180,预测结果明显改善。

Improvement of airfoil turbulent trailing-edge noise semi-empirical prediction formulation

The traditional BPM semi-empirical prediction airfoil turbulent boundary layer trailing edge noise was improved. The traditional BPM semi-empirical prediction formulation overpredicts the spectra in high frequency range at high angle of attack or for thick airfoil. It is found that it was mainly caused by the overestimation of the noise contribution from pressure side source through the analysis and comparison between the traditional BPM semi-empirical prediction formulation and Howe's trailing-edge noise theoretical model. Then the ratio of noise contribution from suction side and pressure side source is improved to the square power of boundary displacement thickness rather than the one power appeared in the traditional BPM semi-empirical prediction formulation. The improved BPM semi-empirical prediction formulation is employed in the airfoil turbulent boundary layer trailing-edge noise prediction, which shows that better results can be obtained from the improved BPM semi-empirical prediction formulation for NACA0012 airfoil at high angle of attack. The prediction for wind turbine airfoil DU-96-W-180 is improved significantly by improved BPM semi-empirical prediction formulation.