Low-frequency unsteadiness of vortex wakes over slender bodies at high angle of attack

查看全文 作　　者：Ma [1]Baofeng;Huang [1]Yu;Liu [1]Tongxin

机构地区：[1]Ministry-of-Education Key Laboratory of Fluid Mechanics, Beihang University

出　　处：《Chinese Journal of Aeronautics》索引2014年第27卷第4期,共9页

基　　金：supported by the National Natural Science Foundation of China(No.11272033) 摘　　要：A type of flow unsteadiness with low frequencies and large amplitude was investigated experimentally for vortex wakes around an ogive-tangent cylinder. The experiments were carried out at angles of attack of 60–80 and subcritical Reynolds numbers of 0.6–1.8×105. The reduced frequencies of the unsteadiness are between 0.038 and 0.072, much less than the frequency of Karman vortex shedding. The unsteady flow induces large fluctuations of sectional side forces. The results of pressure measurements and particle image velocimetry indicate that the flow unsteadiness comes from periodic oscillation of the vortex wakes over the slender body. The time-averaged vortex patterns over the slender body are asymmetric, whose orientation is dependent on azimuthal locations of tip perturbations. Therefore, the vortex oscillation is a type of unsteady oscillation around a time-averaged asymmetric vortex structure. 关键词：低频率细长体涡脱落大迎角粒子图像测速周期振荡时间平均临界雷诺数

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Low-frequency unsteadiness of vortex wakes over slender bodies at high angle of attack

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