四种典型钝体结构绕流风场的三维大涡模拟研究

Numerical simulation of wind flow around four typical bluff bodies using large eddy simulation

高雷诺数条件下采用大涡模型研究缩尺比为1∶200的四种典型体型建筑物(方形、矩形、L形和U形)的钝体绕流现象,在确保连续性和计算效率的条件下提出采用修正的自回归滤波模型模拟入口边界的脉动风速条件,并通过与理论计算结果的对比分析验证所提方法的正确性。对不同体型不同风向下六种计算工况进行瞬态动力分析,研究钝体表面空间风压分布特性及钝体周围流场的竖向和横向风速剖面分布特性,给出钝体对周围流场影响的最大干扰范围。结果表明:钝体迎风面平均压力系数分布较顶面、侧面和背面均匀、稳定,脉动风压系数受涡旋运动状态影响较大,最大值出现在侧风面流场分离、涡旋运动最强处;钝体对周围流场的影响随距离的增大而减小,且对尾流区流场的影响最强,最大干扰范围为0.25H(来流区)、0.4H(屋顶区)、0.5H(侧边区)和3H(尾流区)。

Abstract： Wind flow around 1：200 scaled four typical bluff bodies （S-, R-, L- and U-shaped models） are studied by computational fluid dynamic methods using large eddy simulation （LES） in high Reynolds numbers. Fluctuating wind velocity in inflow boundary is generated by improved auto-regressive model method. The inflow continuity condition of fluctuating wind velocity and computational efficiency are strictly ensured by the proposed method, which is verified by the good agreement between simulation and theory results. Spatial pressure distributions and flow field characteristics of six computational schemes were investigated in detail based on data obtained by transient dynamic analysis and the maximum disturbance scope of flow induced by bluff bodies are proposed. The results show that mean pressure coefficients are much more uniform and stable on front faces than top, side and rear faces. Fluctuating pressure coefficients are influenced greatly by motion state of vortex and the maximum values appears at flow separation on side faces. Velocity profiles of wind flow are disturbed obviously among the four models, especially in weak flow. The disturbed intensity decreases with the distance away from the models. The suggested maximum disturbance scopes away from bluff body are generally 0.25H in inflow zones, 0.4H in roof zones, 0.5H in both side zones and 3H in weak zones.