下击暴流的物理模拟及其在建筑抗风试验研究中的应用

摘要

In order to establish physical simulation ability of downburst and study the wind resistance security of buildings under it,the downburst simulation device has been built up.The downburst simulation device can provide stable and uniform jet flow,which is consistent with the impact wall flow model.As a result,it can simulate downburst effectively.Using the downburst simulation device for the surface wind load tests of the circular cross section high-rise building model and the low plant model,the result shows that the largest mean wind pressure coefficient of the circular section high-rise building model windward side appears on the middle height.The mean wind pressure coefficients of the circular section high-rise building model leeside and side faces are negative,and the mean wind pressure coefficients of the side faces increase with the rising jet wind speed.The wind pressure coefficients distribution of the low plant windward side shows symmetrical distribution along the midcourt line of the windward side,and the middle wind pressure are larger than that of the edge.The negative wind pressure coefficients of the low plant leeside decrease from the middle to the edge,and the smallest negative wind pressure appears in the middle.The largest negative wind pressure of the low plant roof appears on junction of the windward side roof and the leeside roof.%为建立下击暴流物理模拟能力,研究了下击暴流作用下建筑物抗风安全性问题,建成了下击暴流模拟装置.装置能够提供稳定的均匀射流,并与冲击壁流模型相吻合,能有效地模拟下击暴流.将该装置应用于圆形截面高层建筑及低矮大跨厂房在下击暴流作用下的表面风荷载试验研究,试验结果表明:圆形截面高层建筑迎风面的最大平均风压系数出现在建筑中部高度附近,背风面及侧风面的平均风压系数均为负值,且侧风面负压随喷口风速的增加而增大.低矮厂房迎风面风压系数大体沿厂房中线对称分布,中间风压较边缘大;背风面负压由中间向两边递增,中间负压较边缘小;屋顶最大负压出现在迎风和背风屋顶结合处.