正方形排列四圆柱体绕流特性及互扰效应研究

Study on the characteristics and interference effects of flow around four square-arranged circular cylinders

基于计算流体动力学理论,运用大涡模拟方法对雷诺数Re=3900三维正方形排列四圆柱体结构群的绕流问题进行数值计算,主要分析来流攻角与间距比两个参数对四圆柱体结构群流体参数及流场模态的影响。结果表明:来流攻角与间距比均对四圆柱体结构群绕流特性有较强的影响;来流攻角θ=0°、22.5°、45°下,临界间距比分别为3.5、4.0、3.0;间距比的变化会导致下游圆柱表面压力系数分布发生改变;另一方面,间距比较小时,四圆柱体结构之间的互扰作用均以临近效应为主;随间距比增大,上游圆柱尾流对下游圆柱有显著影响,其互扰作用会转变尾激效应。

Based on the computational fluid dynamic theory,the flow around three-dimensional four circular cylinders in the square configuration is investigated numerically under Re=3900 by using large eddy simulation(LES).The effects of spacing ratio and the incidence angle on the fluid force coefficients and flow patterns of four square-arranged circular cylinders are analyzed emphatically.The results indicate that the spacing ratio and the incidence angle have great influences on the fluid characteristics of four square-arranged circular cylinders.The results show that the critical spacing ratios of the flow around four circular cylinders with a square arrangement are 3.5(α=0°),4.0(α=22.5°)and 3.0(α=45.0°),respectively.The variation of the spacing ratio gives rise to the change of the pressure coefficient distribution on the surface of the downstream circular cylinder.On the other hand,at small spacing ratio,the interaction between the four cylinders is mainly the proximity effect.With the increasing of spacing ratio,the wake of the upstream cylinder has a significant effect on the downstream one,and the interaction between the cylinders transforms to the wake interference.