柔性锯齿形尾缘流动分离控制实验的多尺度相干结构研究

本文采用柔性锯齿形尾缘进行了流动分离控制风洞实验。利用高频响热线风速仪测量了翼型尾流场，结合瞬时强度因子迭代算法，在时域、频域提取出多尺度湍流相干结构，分析了弹性振动和柔性形变对扰动传播不稳定性的影响。实验结果表明:尾流中分离区厚度减小5%弦长，柔性锯齿形尾缘跟随来流自适应变形摆动，吸收了约20%的尾缘剪切层中的湍动能，产生的大尺度扰流涡持续传递至前缘剪切层，降低了很大范围低频带宽内的功率谱密度，具有良好的降噪效果；脱落涡中相干结构的振幅和发生频率显著削弱，对尾流分离区边界移动、大型涡包破碎和抑制传播的作用非常明显。

Experimental study on flow separation control by flexible serrated trailing edge based on multi-scale coherent structure analysis

This article reports our recent experimental study of airfoil flow separation control by flexible serrated trailing edge. The experiments were conducted in a straight-type wind tunnel and a hot-wire anemometer was used to measure the velocity profile downstream of the two-dimensional airfoil. Multi-scale coherent structures within the separated shear layers are analyzed both in the time and frequency domains. The results show that the separation bubble thickness decreases by almost 5% of the chord length, the flexible serrated trailing edge vibrates and deforms adaptively and absorbs nearly 20% of the trailing edge shear layer’s energy, perturbation transmits to the leading edge shear layer, and thus the power spectral density decreases significantly in the lower and larger bandwidth to reduce the noise. The coherent structures’ frequency and amplitude also decrease notably, breaking and inhibiting the large vortex package’s transmission obviously in the separation bubble.