外形变化对圆柱体结构绕流特性的影响

Effect of Shape Modification on Flow Characteristics of the Circular Cylinder

基于CFD流体计算平台Fluent计算软件,对雷诺数Re=3900下波浪型圆柱体结构三维绕流问题进行了研究,主要分析波长比(λ/D_(m)=1.8~5.0)与波幅比(a/D_(m)=0.05~0.2)两个关键参数对波浪型圆柱体的绕流特性及其尾流场分布特性的影响且引入了光滑圆柱(UC)计算结果作对比,并进一步揭示其内在的尾流控制机理。研究表明:波浪型圆柱体尾流特性存在强烈的三维效应,节点处与鞍形处流场特性分布存在明显差异;波浪型圆柱尾流区的顺流向时均速度分布呈现出半对称U型,而轴向方向的时均速度分布则呈现出强烈的三维效应;波浪型柱体沿径向方向压力分布也呈现出强烈的三维效应,一般在节点处的压力达到最小值,在中间截面处压力值达到最大;随波幅比增大,阻力系数平均值与脉动性升力系数大致呈现出衰减趋势,并在a/D_(m)=0.2处达到最小值。波浪型柱体结构压差阻力的减少为结构流动控制提供相关支撑。

Using the software Fluent on the computational fluid dynamics(CFD)platform,the threedimensional flow problem of the wavy cylinder at the Reynolds number Re=3900 is studied.The wavelength ratios(λ/D_(m)=1.8~5.0)and the amplitude ratios(a/D_(m)=0.05~0.2)are mainly considered.The influence of the two parameters on the flow characteristics of the wavy cylinders and the distribution characteristics are analyzed in the wake field and the calculation results of the unmodified cylinder(UC)are introduced for comparison.The research shows that there is a strong three-dimensional effect in the flow field distribution between the node and the saddle.The mean streamwise velocity distribution in the wake of wavy cylinder exhibits a semi-symmetrical U shape.The pressure and axial mean velocity distribution of the wavy cylinder in the spanwise direction also exhibits a strong three-dimensional effect.The minimum values of pressure change to the middle plane,while the maximum values are at nodal planes.With the increase of the amplitude ratio,the mean drag coefficient and the fluctuating lift coefficient are generally reduced,and reach minimum values at a/D_(m)=0.2.Finally,the reduction in the differential pressure drag of the wavy cylinder provides relevant support for the flow control.