超大型冷却塔风-雨双向耦合作用机理和气动力分布研究

Wind-rain bidirectional coupled action mechanism and aerodynamic force distribution of super large cooling towers

传统研究大多仅关注风单项驱动雨对于结构表面的冲击效应,均忽略了暴雨对脉动风湍流效应的反作用。针对国内已建成210 m世界最高超大型冷却塔,以风-雨双向耦合算法为核心,基于计算流体动力学(CFD)方法采用连续相和离散相模型分别进行风场和雨滴的模拟迭代。首先,对比研究9种不同风速和雨强组合对塔筒表面风驱雨量、雨滴附加作用力和雨致压力系数的影响规律,揭示风雨耦合场中塔筒速度流线、湍动能强度、雨滴运行速度和轨迹的作用机理,并针对不同工况的塔筒表面压力、雨荷载以及不同高度和角度下的等效压力系数进行了定性和定量的对比分析。在此基础上,提炼出最不利风雨组合工况,并基于非线性最小二乘法原理,以子午向高度和环向角度为目标函数拟合给出了超大型冷却塔等效压力系数的计算公式和对应的二维空间曲面。研究结论可为此类超大型冷却塔在极端气候下的表面荷载精确化取值提供依据,同时加深对风雨共同作用机理的理解。

Traditional studies mostly pay attention to shock effect of rain driven by wind on structural surfaces,but they ignore the reaction of heavy rain on pulsating wind turbulence effect.Here,aiming at 210m high super large cooling towers built in home and being the tallest ones in the world,the wind-rain bidirectional coupled algorithm was taken as the core,wind field and rain drops were iteratively simulated,respectively by using the continuous phase model and the discrete phase one based on the computational fluid dynamics(CFD)method.Firstly,the influence laws of 9 different combinations of wind speed and rain intensity on rainfall driven by wind,raindrop additional action force and wind-induced pressure coefficient of tower tube surface were studied to reveal action mechanisms of tower tube speed streamline,turbulence kinetic energy intensity,and raindrop moving speed and trajectory in wind-rain coupled field.Tower tube surface pressure,rain load,and equivalent pressure coefficient under different heights and angles were qualitatively and quantitatively analyzed under different working conditions.Then,the most unfavorable wind-rain combination working condition was extracted.The calculation formula of equivalent pressure coefficient and the corresponding 2-D space surface for super large cooling towers were fitted taking meridian height and circumferential angle as the objective function based on the principle of the nonlinear least square method.The study conclusions provided a basis for accurately determining tower tube surface loads of such super large cooling towers in extreme weather and deepening the understanding wind-rain combined action mechanism.