二元海水液滴对心碰撞过程数值模拟

为研究海水循环冷却系统中液滴碰撞的基本规律及碰撞结果预测模型,采用流体体积函数(volume of fluid,VOF)方法捕捉两相交界面,利用动态网格自适应技术提高求解精度,对二元海水液滴的对心碰撞过程进行直接数值分析与模拟.首先对氮气中正十四烷液滴的碰撞实验进行数值模拟,验证了数值模型的可靠性.开展了常温常压下等尺寸二元海水液滴对心碰撞数值研究,分析了液滴碰撞过程流场结构及流动机理,研究了不同液滴直径和不同海水浓度对碰撞过程的影响规律,得到了聚合和自反分离两种碰撞结果类型以及二者的临界Weber数.总结出不同Ohnesorge数下海水液滴碰撞结果诺模图.

Numerical Simulation of Head-on Binary Collision Between Seawater Droplets

Numerical simulations of head-on binary collisions between equal-size seawater droplets were conducted with the volume of fluid(VOF)method and the adaptive grid technique,to investigate the collision physics and mechanics of seawater droplets in shower cooling towers.Trial simulations of head-on collisions of tetradecane droplets in nitrogen medium were performed firstly to give results in good agreement with those of the previous experiments.The binary collisions of equal-size seawater droplets were simulated under room temperature and normal pressure conditions.The stream field and flow mechanism of seawater droplets collision were analyzed,and the effects of droplet diameters and concentrations on the collision process were studied.Two different types of collision outcomes were identified:the coalescence and the reflexive separation,for which the critical Weber numbers were given.The schematic diagrams for various head-on collision regimes of seawater droplets at various Ohnesorge numbers were also obtained.