基于完全气动弹性模型的冷却塔风致响应风洞试验研究

Wind tunnel test on wind-induced response of cooling tower based on full aero-elastic model

风荷载是冷却塔设计的控制荷载,完全气动弹性模型风洞试验是研究其风致响应的有效途径。基于此,推导了冷却塔完全气动弹性模型相似关系并用有限元分析方法予以验证,据此相似关系设计并制作了某核电站200 m高超大型冷却塔的1∶400完全气动弹性模型,并在风洞中模拟的B类风场对其风致响应进行测试,试验前对模型的动力特性进行检验。试验结果表明:完全气动弹性模型能较为精确模拟冷却塔结构的质量、刚度和阻尼相似;迎风面的风致变形较大,而其中又以喉部附近最大;背景响应占总响应的主导地位,动力放大效应不明显;风振系数值随高度的增加而减小,各控制点风振系数均值略小于DL/T 5339—2006《火力发电厂水工设计规范》规定值。

Wind loading is the control load for the design of cooling tower,and full aero-elastic model wind tunnel test is an effective way to study wind-induced response of cooling tower.Based on this,similitude relations for cooling tower full aero-elastic model were derived and verified,according to which a full aero-elastic model with geometrical scale of 1∶ 400 was designed and processed for a 200 m high cooling tower of a nuclear power plant.Wind tunnel tests were carried out to measure the wind-induced response in the simulated wind field of terrain category B,before which the dynamic characteristics of the model was tested.The test result indicates full aero-elastic model can accurately simulate the similitude relation of mass,stiffness and damping of prototype cooling tower.Meanwhile,it is found that the maximum displacement occurring in windward side of the throat and the average displacement obtained with full aero-elastic model are almost the same as the result calculated with data measured through rigid model pressure-measurement test.It is also shown that background response plays a major role in the total displacement response and the dynamic amplification effect is not obvious.At the same time,test result shows that gust loading factor decreases with height increasing and the mean value is slightly less than the specified value.