L形和U形三维钝体结构绕流的数值模拟研究

采用大涡模型对L形和U形三维钝体建筑物的绕流特性和风压分布特性进行数值研究。考虑平均和脉动速度入口边界,在雷诺数为1.5×10~5～7×10~5条件下,对2种钝体的9种分析工况进行瞬态动力分析,并将计算结果与已有研究进行对比。研究表明,钝体绕流对周围流场影响的强弱程度依次为尾流区、屋顶区、来流区,影响大小随着流场与钝体之间距离、钝体建筑高宽比、离地高度的增大而减小,且对来流区0.25H、屋顶上部0.4H、左右两侧0.5H、尾流区2.0H范围内流场的影响最大;钝体迎风面风压分布比较均匀,而侧面、背面和顶面受绕流涡旋的影响较大,平均风压分布较为复杂,并与脉动风压分布具有类似的变化趋势。研究结果对结构抗风设计与建筑风环境设计具有一定的参考价值。

Three-dimensional Numerical Study on Wind Field around L-and U-shaped Models

The flow around L-and U-shaped models was studied numerically using the large-eddy simulation approach.Both mean and fluctuating wind were calculated and loaded in inlet boundary condition. Nine cases with different depth-width ratios（1：1,2：1 and 4：1）for L-and U-shaped models were considered. The results of pressure coefficient distribution were compared firstly with the experimental and numerical data provided by other researchers to verify the reliability of the method used in this paper.Velocity profiles and surface pressure distributions of different cases were then investigated and assessed separately. Results show that the wind field in weak regions are greatly influenced by bluff body,and then roof regions and windward regions.The influenced scopes of flow are defined and the maximum scopes away from bodies are 0.25 H in incoming zones,0.4 H in roof zones,0.5 H in both side zones and 2 H in weak zones.The larger the distance away from bluff body,the lower the influenced intensity of flow is. Stable distributions of mean pressure coefficients can be found on windward faces of bluff body.However, mean pressure coefficients on side,rear and roof faces are influenced greatly by vortex motion and show less regular characteristics relatively.Both mean and fluctuating pressure coefficients have similar variation tendency.The results of this paper will provide helpful references for structural wind-resistant design and also wind environment design.