圆柱绕流尾迹对壁湍流相干结构影响的实验研究  

Experimental study on coherent structures in wall turbulence interacting with a circular cylinder wake

作　　者：姜楠[1] 李悦雷[1] 

机构地区：[1]天津大学力学系天津市现代工程力学重点实验室,天津300072

出　　处：《实验流体力学》2007年第3期8-13,共6页Journal of Experiments in Fluid Mechanics

基　　金：教育部新世纪人才基金;国家自然科学基金(10002011);(10232020)联合资助项目

摘　　要：对边界层外区的圆柱尾迹流动结构对边界层近壁区相干结构的影响进行了实验研究。实验在低湍流度风洞中进行,将圆柱放置于yc≈1.1δ（δ为边界层厚度）处,利用热线风速仪分别测量了沿流向不同位置边界层内的瞬时脉动速度信号,并分别比较了位于x/d=1、2、3、4、5、10、15、20、30,y^＋=10-1000范围内的壁湍流相干结构条件相位平均波形及其统计特性。发现圆柱绕流尾迹对平板边界层内相干结构有明显的影响,圆柱绕流尾迹虽然使壁湍流相干结构从喷射向扫掠转变阶段的强度减弱,但壁湍流相干结构的发生概率增加,总体上促进湍流产生,使湍流边界层增厚,壁面摩擦切应力和壁面摩擦速度均增加,从而肯定了湍流边界层外层流动中产生的扰动与近壁区相干结构猝发的生成和发展有直接联系,壁湍流相干结构猝发是外区流动中产生的扰动与湍流边界层内区共同作用产生的这一结论。The experiment is carried out to investigate coherent structures in the near wall region of turbulent boundary layer interacting with the wake of a circular cylinder in the outer region of turbulent boundary layer. The circular cylinder lies perpendicular to the mean flow direction, parallel to the wall and at the height of yc≈1.1δ（where δ is the thickness of the boundary layer）. Time series of instantaneous velocity at different locations in normal direction and longitudinal direction in turbulent boundary layer have been finely measured using hot-wire anemometer in a wind tunnel. Phase-averaged waveform and statistic character of coherent structure in the region of x/d = 10,20,30 and y^＋ = 10- 1000 are acquired using wavelet transformation and conditional sampling method. The result shows that the effect of circular cylinder wake on coherent structure is evident. Although circular cylinder wake weakens the coherent structures＇ intensity in the course of transition from eject to sweep, the probability of coherent structure generation increases, the turbulent boundary layer is thickened, the skin friction velocity and wall shear stress increase and turbulence production is promoted in general with the interaction of the circular cylinder wake. The direct relationship is further confirmed between production and evolution of coherent structure burst in wall turbulence and the disturbance in the outer region of turbulent boundary layer. Burst of coherent structure in wall turbulence is the result of interacting between tween the outer region disturbance and near-wall region of turbulent boundary layer.

关 键 词：圆柱绕流尾迹 湍流边界层 近壁区域 相干结构 猝发 

分 类 号：O357[理学—流体力学]