考虑内外压共同作用的大型冷却塔风荷载分析

Analysis of wind load on large hyperbolic cooling tower considering interaction between internal and external pressure

针对冷却塔内外压的共同作用问题,制作能进行内外压同步测量的风洞试验模型,分析不同表面粗糙度下内外表面的风压分布,探讨底部有无人字柱模型内外表面风压的差别,并比较考虑内压与否时平均风致响应的差别。研究表明:模型表面越光滑,外表面的最大负风压越大。模型底部有人字柱和无人字柱对内压的影响较大,内表面平均风压系数分别约为-0.4和-0.7。内压作用一定程度地可视为均匀环压,考虑内压会对环向薄膜应力产生影响。

In order to study the interaction between the internal pressures and external pressures on cooling tower,a wind tunnel model was made which can make possible the simultaneous measurement of internal and external pressures.The distribution of internal and external pressures under different surface roughnesses is investigated.The difference between the models with and without A-shape columns in the bottom is analyzed.Then the difference of the mean wind-induced responses considering and disregarding the internal pressures is also investigated.Results from study show that,if the model surface is smoother,the maximum negative external pressures are bigger.The models with and without A-shape columns in the bottom have significant difference of the internal pressure coefficients,whose mean values are about-0.4 and-0.7,respectively.The internal pressure can be approximately considered as even pressure,which will result in the circumferential membrane stresses of cooling tower.