This paper deals with the topic of upper surface blowing noise. Using a model-scale rectangular nozzle of an aspect ratio of 10 and a sharp trailing edge, detailed noise contours were acquired with and without a subsonic jet blowing over a flat surface to determine the noise source location as a function of frequency. Additionally, velocity scaling of the upper surface blowing noise was carried out. It was found that the upper surface blowing increases the noise significantly. This is a result of both the trailing edge noise and turbulence downstream of the trailing edge, referred to as wake noise in the paper. It was found that low-frequency noise with a peak Strouhal number of 0.02 originates from the trailing edge whereas the high-frequency noise with the peak in the vicinity of Strouhal number of 0.2 originates near the nozzle exit. Low frequency (low Strouhal number) follows a velocity scaling corresponding to a dipole source where as the high Strouhal numbers as quadrupole sources. The culmination of these two effects is a cardioid-shaped directivity pattern. On the shielded side, the most dominant noise sources were at the trailing edge and in the near wake. The trailing edge mounting geometry also created anomalous acoustic diffraction indicating that not only is the geometry of the edge itself important, but also all geometry near the trailing edge.

中文翻译：

---

亚音速上表面吹动的噪声源定位和缩放

本文主要讨论上表面吹气噪声。使用长宽比为 10 的模型比例矩形喷嘴和尖锐的后缘，在使用和不使用亚音速射流吹过平坦表面的情况下获取详细的噪声轮廓，以确定作为频率函数的噪声源位置。此外，还对上表面吹气噪声进行了速度缩放。发现上表面吹气显着增加了噪音。这是后缘噪声和后缘下游湍流的结果，在论文中称为尾流噪声。结果表明，斯特劳哈尔数峰值为 0.02 的低频噪声起源于后缘，而斯特劳哈尔数峰值为 0.2 附近的高频噪声起源于喷嘴出口附近。低频（低 Strouhal 数）遵循与偶极子源相对应的速度缩放，而高 Strouhal 数为四极子源。这两种效果的顶点是心形指向性模式。在屏蔽侧，最主要的噪声源位于后缘和近尾流。后缘安装几何形状还产生了异常声学衍射，表明不仅边缘本身的几何形状很重要，后缘附近的所有几何形状也很重要。