过冷水滴碰撞导线表面结冰机理的实验研究

Experimental Study on the Freezing Mechanism of Super-cooled Water Droplets Impacting on a Wire

导线覆冰是一种随机发生的自然现象,曾对电网的安全构成严重危害。目前人们对过冷水滴碰撞导线结冰过程机理认识尚不太清楚。文中对过冷水滴碰撞导线表面结冰机理进行了实验研究,通过对单一过冷水滴碰撞圆柱金属表面冻结的动态行为进行高速拍摄,揭示了该结冰过程形态特征,并从大量实验数据中分析得到了过冷水滴分别以2.2m/s和4.3m/s的速度撞击不锈钢、紫铜、铝等表面瞬时结冰边界条件的统计数据。同时还对过冷水滴流量从0.6滴/s到2.2滴/s,环境温度从-2℃～-8℃时导线覆冰增长动态过程影像及形态变化进行了研究和归纳分析。

Ice accretion on power lines is a random natural phenomenon and may seriously harm to the safety of power network.However,the mechanism of the freezing process of super-cooled water droplet impacting on wires is still not fully understood at present.In this paper,an experimental investigation on the freezing mechanism of the super-cooled water droplet impacting on a cold wire surface is performed.The morphological characters and the impact dynamics of a single super-cooled droplet collide on the cylindrical metal surfaces have been revealed with high-speed photographing.An instantaneous freezing phenomenon of the super-cooled impacting droplet was identified and the condition boundary for this kind of freezing was obtained statistically from the experimental data for the surfaces of stainless steel,copper and aluminum,on which the super-cooled droplets impinging with speeds of 2.2 m/s and 4.3 m/s.Meanwhile,the dynamic images of the ice accretion on a real aluminum wire with the droplet impinging rate from 0.6 to 2.2 drops/s in ambient temperature from？-2℃ to？-8℃ were obtained and the morphological behaviors of these accretion processes were analyzed.