液滴碰撞水平壁面实验研究

Research on experiments of droplet impacting on a flat surface

采用高速摄像仪结合像素分析法观测了液滴碰撞水平干壁面铺展、收缩、飞溅等动力学形态变化,并定量获得了液滴铺展系数和铺展速度随无量纲时间的变化规律。实验结果表明:液滴的铺展系数和铺展速度与碰撞速度和液滴初始直径密切相关,碰撞速度越大,液滴的铺展系数和铺展速度越大,铺展速度在撞壁初始阶段变化明显,随时间逐渐趋于稳定;液滴初始直径越大,铺展系数越大,其临界飞溅速度越小。无量纲分析得出:液滴的最大铺展系数与雷诺数密切相关,液滴达到最大铺展系数所需无量时间与韦伯数不相关。

A droplet impacting on a flat dry surface is experimentally investigated by using the high speed camera.The phenomenon of spreading,breakup and splashing during droplet impacting are observed.The results show that the spreading coefficient and velocity are closely related to the impacting velocity and initial diameter of droplet;the droplet with lager impacting velocity has larger spreading coefficient and velocity;the maximum spreading velocity appears at the initial stage of impact;the droplet with larger initial diameter has a larger spreading coefficient and smaller critical splashing velocity.The dimensionless analysis shows that the maximum spreading coefficient is closely related to Reynolds number,the dimensionless time of maximum spreading coefficient is uncorrelated to Weber number.