液滴高速撞击固体板面过程的研究

Study of Liquid Droplet Impacting on a Solid Surface with High Velocity

以旋风分离器内的液滴运动情况为背景,对不同液滴撞击板面现象进行了实验研究,通过分析不同撞击速度下的铺展现象发现,初始撞击速度对铺展过程影响很大,且与飞溅参数密切相关,即高速撞击易发生飞溅现象;在液滴的铺展过程中粘性力与表面张力不断地克服惯性力作用,直至达到最大铺展直径并回缩。相同条件下的同一液滴,增加撞击速度铺展直径随之增大;对于不同液滴,在相同撞击速度下,粘性较小的液滴易于铺展,最大铺展直径较大。此外,在对所测数据分析后发现,文献中提到的液滴铺展直径与铺展时间之间的幂函数关系只有在低速撞击条件下(速度小于6 m/s)适用,而本文提出的指数函数能更好地预测液滴铺展直径与时间的关系。

Impact of liquid droplets on a solid surface was studied experimentally using a high speed camera on the background of droplet movement in the cyclone type separator. It was found that the spreading process of a droplet was strong influence by initial velocity and splash phenomenon was easy to occur at high impact velocity. Impacting droplets spread on the surface until liquid surface tension and viscosity overcame inertial forces, after which they recoiled off the surface. For some kind of liquid, the spreading diameter increased as the impact velocity increased. Comparing with high viscosity, a low viscosity liquid （water） was easy to spread. In addition, the model referred to the literature was only fitting for low impact velocity （u〈6 m/s）. The spreading model presented in this paper could predict well the spontaneous spreading of a liquid drop on a solid surface.