仿生学覆羽控制翼型流动分离实验  

Experiments on flow separation control with bionic coverts

作　　者：巩绪安 张鑫[2] 马兴宇 范子椰 姜楠[1,3] GONG Xu’an;ZHANG Xin;MA Xingyu;FAN Ziye;JIANG Nan(Department of Mechanics,School of Mechanical Engineering,Tianjin University,Tianjin 300354,China;State Key Laboratory of Aerodynamics,China Aerodynamics Research and Development Center,Mianyang 621000,China;Tianjin Key Laboratory of Modern Engineering Mechanics,Tianjin 300354,China)

机构地区：[1]天津大学机械工程学院力学系,天津300354 [2]中国空气动力研究与发展中心空气动力学国家重点实验室,绵阳621000 [3]天津市现代工程力学重点实验室,天津300354

出　　处：《空气动力学学报》2021年第6期184-195,I0003,共13页Acta Aerodynamica Sinica

基　　金：国家自然科学基金(11902218,11732010,11972251,11872272);中德合作研究小组计划(GZ1575);气动噪声控制重点实验室开放课题(ANCL20200105)。

摘　　要：“高效率、低噪声”的飞行特点为猫头鹰披上了一层神秘的面纱。本文根据其翅膀覆羽的仿生学构造,设计了新型的柔性锯齿形旋涡发生器,铰接在NACA0018二维翼型各弦长位置处。通过风洞实验,研究了不同面密度柔性材料的流动分离控制效果。实验中,首先利用高时间分辨率的热线风速仪单点扫掠测量尾流区的流场信息,通过小波变换同时在时域、频域对各个尺度涡包的破碎和掺混过程展开分析,确定湍动能较高的特征测点位置后,利用两根热线探针双通道同时测量,得到不同位置的同步流场数据,通过互相关分析,在时域和频域上得到不同空间位置之间扰动的相关性,并结合CCD高速相机的拍摄结果,研究柔性材料的自适应形变规律与扰流涡之间的关系。实验结果表明:中等面密度的柔性材料控制效果较优,安装在尾缘时可以有效吸收附近34%的湍动能用于自适应地振动和变形;剪切层的上边界向下移动0.05倍弦长,尾缘和前缘剪切层的低频段功率谱密度分别下降了70%和50%,前缘剪切层的大尺度结构被破碎为小尺度结构,具有潜在的降噪效果,两剪切层的相关性在频域上得到显著增强。当旋涡发生器的安装位置向前缘移动时,其在逆压梯度下产生的扰动将向低频段转移,大尺度的扰流涡可以诱导分离泡的上边界下移0.1倍弦长。Inspired by the owl's high-efficiency and low-noise flight mode,this work studies the bionic structure of its coverts,and designs a new type of flexible serrated vortex generators with different flexible materials,which are hinged at several different locations of a two-dimensional NACA0018 airfoil in the wind tunnel,to study the flow separation control effect of flexible materials with different areal densities.In the experiment,a single-point sweep of a hot wire anemometer with high time resolution was used to measure the flow field information in the wake region,and the wavelet analysis was used to extract multi-scale structures in the time-frequency domain.After points with high kinetic energy were obtained,a two-channel hot-wire measurement was used to acquire synchronous velocity data at different locations,and the correlation between disturbances at different spatial positions was obtained in both the time and frequency domains through a cross-correlation analysis.A high-speed CCD camera was used to record the movement and adaptive deformation of the vortex generators,and the relation with disturbance vortices was analyzed.The experimental results suggest that,when installed on the trailing edge,medium density vortex generators can effectively absorb 34%of the nearby turbulent kinetic energy.The shear layer moves downstream by 0.05 times the chord length,and the low-frequency power spectral density of the trailing-edge and leading-edge shear layer is decreased by 70%and 50%,respectively.Large-scale structures of the leading-edge shear layer were broken into small-scale ones,and the correlation between the leading-edge and trailing-edge shear layers in the frequency domain was considerablely increased.When the installation location moves upstream,perturbations generated under the adverse pressure gradient were shifted to a low-frequency bandwidth,and the large-scale vortex can induce the separation bubble to move downstream by 0.1 times the chord length.

关 键 词：仿生学 流动分离控制 柔性锯齿 小波分析 互相关函数 

分 类 号：V211.7[航空宇航科学与技术—航空宇航推进理论与工程]