湿下击暴流作用下建筑立面雨压分布特性的数值分析

Numerical analysis of distribution characteristics of rain pressure on building facade under downburst accompanied with rain

下击暴流作用于建筑物将产生严重破坏,虽然其引起的风荷载已有较多研究,但均局限于无降雨的干下击暴流作用情况。目前,已有研究表明风雨环境下的建筑风驱雨(wind-driven rain,WDR)可能产生较显著的雨压荷载,因此对有降雨的湿下击暴流作用下建筑立面WDR雨压开展研究十分必要。基于建筑WDR数值模拟方法,引入欧拉多相流模型,采用RNG k-ε湍流模型封闭求解N-S方程,模拟求解湿下击暴流的建筑WDR场,侧重考虑建筑距风暴中心位置及雨强变化的情况,分析迎风面WDR雨压分布特性并与干下击暴流作用下的纯风压进行比较。结果表明:随着建筑远离风暴中心,雨压存在先增大后又减小的现象;迎风面沿竖直中心线上同处的雨压可达纯风压的20%,且迎风面较大风压、雨压均出现在建筑底部位置,因此湿下击暴流风压与雨压联合作用将比较显著,需要考虑其对建筑的影响。

Downburst can lead to serious structure damage. There is a large amount of research work on the wind load of structure under downburst to be done in the past, but these researches are limited to the downburst accompanied with no rain. Currently, the existing researches have shown that the rain-pressure load on building facades caused by wind-driven rain(WDR) is significant, thus it is quite necessary to conduct the study of WDR rain pressure on building facades under downburst accompanied with rain. By virtue of WDR numerical simulation method which is based on Eulerian multiphase model and where N-S equations are solved by closure with RNG ?k-ε turbulence model, WDR field around building is simulated under downburst accompanied with rain. The distribution characteristics of WDR rain pressure on the windward facade and the difference compared with pure wind pressure for different locations away from storm core and for various horizontal rainfall intensities are analysed emphatically. The results show that with the increase of distance between the storm core and the building, the rain pressure first increases and then decreases. It can account for 20% of the pure wind pressure along the vertical center line on the facade, and the maximum rain pressure and wind pressure occur at the bottom of building. Therefore, the combined effect of wind pressure and rain pressure on building under downburst accompanied with rain may be significant, so it is quite necessary to take into account the effect.