环状大悬臂挑篷风载特性与风场绕流分析

Wind pressure and wind field characteristics around long cantilever annular roofs

基于FLUENT软件并引入k-ε湍流模型,对环状大悬臂挑篷屋盖风载和风场进行模拟分析。数值计算分析风向角、屋盖倾角、看台后部通风率、挑篷开洞、有无后挑等参数对挑篷屋盖风压分布的影响;针对屋盖周围气流的绕流特性,分析设置屋盖竖向气动导流板和在挑篷外环边缘附近开洞对降低屋盖负风压的作用。研究结果表明:无论风向角如何变化,水平挑篷屋盖上风压均以吸力为主,较高的吸力分布在迎风的前缘位置;屋盖倾角宜设在0°～15°范围,过大或过小均不利于结构抗风;增大结构迎风面的通风率有利于减小水平屋盖的平均风压;屋盖是否后挑对水平屋盖上表面的风压影响较小;增设屋盖竖向导流板可减低水平屋盖前缘局部极值风压;在环状挑篷外环边缘附近开洞可较明显减小屋盖风压。

Wind pressure and wind field around long cantilever annular roofs were simulated numerically by using commercial software FLUENT and k-6 turbulence model. The effects of key parameters such as the coming wind direction, roof angle, ventilation rate, openings on the roof, and cornice on wind pressure distribution around the roof were analyzed, and the effects of vertical aerodynamic control plates fixed to and openings along the roof＇ s out-edge on wind pressure distribution of annular roof were investigated. The results show that the negative wind pressure occurs on the upper surface of horizontal roof under any coming wind angle, and higher negative pressure always appears at the out-edge of the roof. The optimal inclination angle of roof should be among the range of 0° - 15°. The increase of ventilation rate on windward surface of structural system can reduce mean wind pressure on the horizontal roof, while roof cornice has little influence on wind pressure. Both vertical aerodynamic control plates fixed to the roof and openings along the perimeter of the roof can obviously reduce wind pressure of horizontal roof effectively.