典型矩形八塔超大型冷却塔塔群风致干扰效应试验

Wind tunnel investigation on interference effect of eight grouped super large cooling towers with rectangular arrangement

以某拟建183.89 m超大型冷却塔的矩形八塔组合塔群的1:200比例尺模型为研究对象,进行刚体模型测压风洞试验,研究高密度冷却塔群的风致干扰效应,给出受扰塔在16个来流方向下的喉部断面压力系数分布以及结构整体阻力、升力系数,分析形成显著不利干扰的原因。研究结果表明:环向压力系数分布对于受扰冷却塔表面风致效应的反应最准确、最直接,但结果形式繁杂;而结构整体气动力(阻力、升力系数的均值和根方差)简单、明确;与压力系数相比,基于结构整体的气动力可以较准确地确定不利来流工况;在典型不利来流工况下,受扰塔塔体喉部断面的压力系数分布变化特征符合通道作用的机理;高频天平测力试验结果与刚体模型测压试验结果不一致,在现有技术条件下,仅将高频天平测力试验结果作为测压试验结果的补充。

Based on cladding wind loads produced by simultaneous pressure measurements on a 1：200 rigid super large cooling tower model （the prototype column-supported hyperboloidal shell is of 183.89 m in height） in TJ-3 wind tunnel of Tongji University, interference effect of eight grouped cooling towers with a close rectangular arrangement was studied. Distributions of mean and fluctuating pressure coefficients around some throat sections of the principal tower were obtained firstly considering different interference effects corresponding to 128 situations （16 angles of incidence for each of the eight cooling tower positions）, which accurately and straightforwardly demonstrate the unpredictable changes of wind loads among different situations. Secondly, the overall loads （mean and root-mean-square drag/lifl） were calculated. To obtain better understanding of strong interference mechanism, the pressure coefficient distributions of tower No.5 with the most adverse angle of incidence were then carefully studied. Finally, force balance tests on a 1：500 lumber tower model were applied to obtain the overall loads directly. The results show that the pressure coefficient distributions accurately and straight forwardly demonstrate the unpredictable changes of wind loads in different situations, and the simple overall loads indicate adverse situations correctly. The asymmetric feature of tower number 5＇s average pressure pattern in that unsafe situation is mainly caused by the accelerated flow gotten from a narrow passage between neighboring cooling towers, and the corresponding fluctuating pressure pattern is strongly influenced by the wake of an upstream interfering tower. The base balance technique can not replace the traditional pressure measurement technique at present.