微米级液滴撞击低温球形颗粒的涂覆冻结

Impact of Coating Droplet on Low Temperature Spherical Particles

对微米级液滴撞击低温球形表面的动态行为进行了可视化实验.研究了液滴直径、球面温度等因素对微米级液滴撞击过程的影响及液滴撞击直径3mm和5mm金属钢球的冻结过程.当实验球面温度分别为–20℃和–30℃时,液滴撞击低温金属钢球表面时液滴铺展后迅速回缩成塔形状然后缓慢的铺展直至稳定状态,与常温状态下相比,液滴形态没有明显的振荡过程.结果表明:撞击速度越大,液滴具有的初始动能越大,液膜最大铺展弧长越大.随着载体颗粒直径的增加,液膜最大铺展弧长也随之增加,液膜的厚度却随载体颗粒直径的增加而减小;随着液滴直径的增加,液膜铺展弧长及液膜厚度都随之增加.通过实验数据统计分析可知,环境温度的显著水平最高,然后依次为液滴直径、载体颗粒直径.

In this research,a visual experiment of the dynamic behavior of microsphere droplets impacting cryogenic spherical surfaces was performed.The influence of droplet diameter,spherical temperature and other factors on the impact process of micron droplets and the freezing process of droplets impacting metal balls of 3 mm and 5 mm diameters were studied.When the droplet impacted the surface of a metal ball of the spherical temperature at –20℃ and –30℃,the droplet quickly retracted into a tower shape and spread slowly until it reached a stable state.Compared with that at room temperature,there is no obvious oscillation in the morphology of the droplet.The results show that the larger the impact velocity,the larger the initial kinetic energy of the droplet,the larger the maximum spreading arc length,and the larger the arc length of the liquid film;while with the increase of the carrier particle diameter,the thickness of the liquid film decreases and the maximum spreading arc length of the film increased.With the increase of the droplet diameter,the spreading arc length of the liquid film and the thickness of the liquid film both increased.Statistical analysis of the experimental data shows that the most influential factor is environmental temperature,followed by droplet diameter and carrier particle diameter.