单窄条控制件对横向振荡柱体尾流2P模式旋涡脱落的改变  

THE SINGLE STRIP-INDUCED CHANGE OF 2P-MODE VORTEX SHEDDING IN THE WAKE OF A TRANSVERSELY OSCILLATING CYLINDER

作　　者：曹梦圆 金华斌[1] 邵传平[1] Cao Mengyuan;Jin Huabin;Shao Chuanping(Institute of Fluid Measurement and Simulation,China Jiliang University,Hangzhou 310018,China)

机构地区：[1]中国计量大学流体检测与仿真研究所,杭州310018

出　　处：《力学学报》2018年第4期734-750,共17页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金资助项目(11172286;11572305)

摘　　要：横向强迫振荡柱体尾流控制是柱体涡激振动控制的基础,在海洋、土木等工程中具有重要意义.横向强迫振荡柱体尾流中存在一种锁频旋涡脱落模式,即在一个振荡周期内柱体上、下侧各脱落旋转方向相反的一对涡,称为2P模式.本文将相对宽度b/D=0.32的窄条控制件置于横向强迫振荡柱体下游,对振幅比A/D=1.25,无量纲振频f_eD/V_∞=0.22,雷诺数Re=1 200的2P模式旋涡脱落进行干扰,并通过改变控制件位置,研究旋涡的变化规律.采用二维大涡模拟和实验验证方法进行研究,在控制件位置范围0.8 X/D 3.2,0.4 Y/D 3.2内,得到了2P,2S,P+S和另外6种新发现的旋涡脱落模式,并对各模式旋涡的形成过程作了详细描述.在控制件位置平面上给出了各旋涡模式的存在区域,画出了旋涡脱落强度的等值线图,并发现在一个相当大的区域内,旋涡脱落强度可减小一半以上,尾流变窄.发现柱体大幅振荡引起的横向剪切流在旋涡生成中起关键作用.探讨了控制件对横向剪切流的影响,分析了控制件在每种旋涡模式形成中的作用机制.The control of vortex shedding from a forced oscillating cylinder is the basis of control of vortex-induced cylinder vibration, and of significance in civil and ocean engineering. A lock-on mode of vortex shedding called 2 P mode exists in the wake of an oscillating cylinder, i.e., in a period of oscillation, a pair of vortices shed from each side. A strip element of width b/D = 0.32 is used and set in the wake to influence the 2 P mode vortex shedding at oscillating amplitude A/D = 1.25, frequency f_eD/V_∞= 0.22, and Reynolds number Re = V_∞D/ν = 1 200. Using the method of 2D large eddy simulation with experimental confirmation, we find that with the change of strip position in the area 0.8 X/D 3.2,0.4 Y/D 3.2, vortex shedding is changed between 2P, 2S, P＋S and other 6 new modes. The detailed generation process of every mode of vortex shedding is described in the paper. The zones of the modes and the contours of vortex strength are figured out on the plane of strip position. It is shown that vortex strength can be reduced by 50% or more and the wake is narrowed if the strip is set at places in a considerably large region. The transverse shear flow induced by large amplitude cylinder oscillation plays a key role in the generation of vortex shedding. The influence of the strip on the transverse shear flow is discussed and the mechanism of the strip function to the formation of every mode of vortex shedding is analyzed.

关 键 词：涡激振动 强迫振荡 旋涡脱落 控制 

分 类 号：O35[理学—流体力学]