透水框架的三方柱绕流数值分析

针对四面六边透水框架按高度分层后形成等边三角形布置的三方柱绕流问题进行了数值模拟，分析不同间距比l/d=1.5，2，3，4，5，7下流场分布和各方柱的升、阻力系数以及斯特劳哈尔数的特性。研究结果表明:当l/d=1.5~7时，B，C柱尾流场经历了近处漩涡掺混到近处漩涡分离，远处漩涡掺混到远处漩涡分离，最后形成各自独立的方柱绕流；在l/d=2时，各方柱的平均阻力系数明显减小，并且通过对流场分析发现此间距比下对水流的减速效果最明显；由于B，C柱的存在与单方柱绕流有很大区别:在流场方面，l/d=1.5时，B，C柱限制A柱边界层剪切带的卷起，随间距比的增加这种现象逐渐消失；在动力特性上，A柱的阻力系数明显小于单方柱绕流情况。斯特劳哈尔数Sr随间距比的增大而逐渐增大并趋近于单方柱绕流的值。

Numerical simulation of flow around three square columns

The triangular taper penetrating frame which was stratified by the height forms the flow around the three square columns to form an equilateral triangle arrangement. After the flow around the square columns, analyzing the features about distribution of the flow field and the lift and drag coefficients and the Strouhal number under the conditions of different spacing ratios was carried out in this paper. Within the limits of l/d=1.5~7 B and C column wake fields have experienced the process from near vortex mixing with near vortex separation and from far vortex mixing with far vortex separation. The B and C columns form flow around the square columns independently. When l/d=2, the average of the drag coefficients of each square column decreased significantly. And under the distance the slowing effect of water flow is most obvious; As a result of the existence of B and C columns and there is a great difference in the flow around a single square column: in terms of flow field in the l/d=1.5, B and C columns limited the furl of boundary layer shear zone of A. With the increase of distance this phenomenon will gradually disappear. On the dynamic characteristics, the drag coefficients of A column are lower than that of flow around the single square column. The Strouhal number Sr that increases along with the increase of spacing ratios is approaching to the Strouhal number Sr that was flowing around the single square column.