This paper investigates the effect of airfoil shape on trailing edge noise. The boundary layer profiles are obtained by XFOIL and the trailing edge noise is predicted by a TNO semi-empirical model. In order to investigate the noise source characteristics, the wall pressure spectrum is decomposed into three components. This decomposition helps in finding the dominant source region and the peak noise frequency for each airfoil. The method is validated for a NACA0012 airfoil, and then five additional wind turbine airfoils are examined: NACA0018, DU96-w-180, S809, S822 and S831. It is found that the dominant source region is around 40% of the boundary layer thickness for both the suction and pressure sides for a NACA0012 airfoil. As airfoil thickness and camber increase, the maximum source region moves slightly upward on the suction side. However, the effect of the airfoil shape on the maximum source region on the pressure side is negligible, except for the S831 airfoil, which exhibits an extension of the noise source region near the wall at high frequencies. As airfoil thickness and camber increase, low frequency noise is increased. However, a higher camber reduces low frequency noise on the pressure side. The maximum camber position is also found to be important and its rear position increases noise levels on the suction side.

中文翻译：

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翼型对后缘噪声的影响

本文研究了机翼形状对后缘噪声的影响。边界层剖面由 XFOIL 获得，后沿噪声由 TNO 半经验模型预测。为了研究噪声源特性，将壁压谱分解为三个分量。这种分解有助于找到每个翼型的主要源区域和峰值噪声频率。该方法针对 NACA0012 翼型进行了验证，然后检查了另外五个风力涡轮机翼型：NACA0018、DU96-w-180、S809、S822 和 S831。发现主要源区域是 NACA0012 翼型的吸力侧和压力侧边界层厚度的 40% 左右。随着翼型厚度和弯度的增加，最大源区在吸力侧略微向上移动。然而，翼型形状对压力侧最大声源区域的影响可以忽略不计，除了 S831 翼型，它在高频处表现出靠近壁面的噪声源区域的扩展。随着翼型厚度和外倾角的增加，低频噪声增加。然而，较高的外倾角会降低压力侧的低频噪音。最大外倾角位置也很重要，它的后部位置增加了吸力侧的噪音水平。