油水分离过程中液滴碰撞动力学数值模拟

Numerical simulation of droplet collision dynamics in oil-water separation

采用流体体积法对等径水滴在油相中的二元非对心碰撞过程进行了数值模拟研究,得到液滴碰撞后的变化规律及不同We和不同碰撞参数(B)下的碰撞结果,并对形成机理进行了分析,形成基于油-水两相体系的液滴碰撞结果的区域分布图。模拟结果表明,水滴在油相中的碰撞结果包括聚结和破碎两种方式;相同B下,随着We的增加液滴碰撞过程发生振荡的周期逐渐变长,且伴随有旋转运动;We相同、B不同时,液滴碰撞接触时间随B的增加而推迟,碰撞后发生旋转的角度也随之增大。当We<30时,液滴在所有参数下碰撞结果均为聚结;当We>37时,液滴在所有参数下碰撞结果均为破碎,表明碰撞结果只与We有关;而当We在30~37之间时液滴碰撞结果与We和B均有关。

In order to reveal the collision regimes of discrete droplet in oil-water system,the offcenter collision process of two droplets with equal diameter in the oil phase was simulated by fluid volume method.The collision results of two droplets with equal diameter in the oil phase were obtained under the condition of different We and different collision parameter(B),and the mechanisms of the results were analyzed.It is indicated from the research that the collision results include coalescence and breakup.With a certain B,the shape recovery time after collision increases with the We increase,and is accompanied by a rotational motion.For a certain We,the contact time of the two droplets is delayed with the B increase,and the rotation angle after collision is increased with the B increase.It is found that if the We is less than 30 or greater than 37,the collision result of water droplets is coalescence or breakup,respectively,which means that the results are determined by the We and are independent from B.However,if the We is between 30 and 37,the collision results of water droplets are determined by We and B.