液氮-冰粒射流水滴冻结与冲蚀试验研究

Experimental study on the solidification and erosion of liquid nitrogen-ice particle jet droplets

为了研究液氮-冰粒射流的形成过程和冲击效果,采用可视化试验研究了水滴凝固过程中内部温度及外部特征变化情况,成功调制出液氮-冰粒射流,并进行靶件冲蚀试验。结果表明:体积为5μL的水滴在液氮中(-196℃)凝固内部温度变化分为预冷、凝固、冷却3个阶段,且水滴凝固速度较快,可在1.5 s内完成凝固;水滴凝固时,首先在外侧形成冰壳,再逐步向内凝结,由于体积变化,会导致冰粒局部破裂,需对冰粒体积进行优选;设计并加工了液氮-冰粒射流试验装置;通过靶件冲蚀试验,证实了液氮-冰粒射流的冲击效果显著好于纯液氮射流,在聚丙烯聚合物上的冲击除漆效果优于在铝合金板上的冲击效果。研究成果为液氮-冰粒射流的发展提供了理论基础。

In order to study the formation process and impact effect of liquid nitrogen-ice jet,the changes of internal temperature and external characteristics during the solidification of water droplets were studied by visual experiments.The liquid nitrogen-ice jet was successfully modulated and the target erosion experiment was carried out.The results show that the internal temperature of water droplets with a volume of 5μL in liquid nitrogen(-196℃)can be divided into three stages:pre-cooling,solidification and cooling.The water droplets have a fast solidification speed and can be solidified within 1.5 s.Visualization experiments show that when water droplets solidify,ice crust is formed on the outside first,and then gradually condenses inward.Due to the volume change,the ice grains will break partially,so the volume of ice grain should be optimized.The experimental device of liquid nitrogen-ice jet was designed and manufactured.Through the target erosion experiment,it is confirmed that the impact effect of liquid nitrogen-ice jet is significantly better than that of pure liquid nitrogen jet.The effect of paint removal on polypropylene polymer is better than that on aluminum alloy plate.The research results lay a foundation for the development of liquid nitrogen-ice jet.