空气动力型绝缘子表面不同区域的水滴撞击特性

Water Droplet Impingement Characteristics on Different Regions of Aerodynamic Insulator Surface

绝缘子严重覆冰会引发闪络进而导致电网停电事故,研究水滴撞击绝缘子表面的流场和运动特性对了解绝缘子的覆冰形成过程具有重要意义。以空气动力型绝缘子为研究对象,基于Lagrange法,通过数值求解覆冰过程中绝缘子外部连续气流场和水滴运动轨迹,提出一种以区域分割方式数值计算绝缘子表面不同区域水滴碰撞系数的方法;分析了风速和水滴中值体积直径（MVD）对水滴碰撞系数的影响,并进行了试验验证。研究结果表明：对于空气动力型绝缘子,其钢帽和绝缘子伞边缘碰撞系数差别不大（〈3%）,2个区域的碰撞系数都远大于迎风侧绝缘子伞表面碰撞系数（高60%-190%）;迎风侧绝缘子伞表面的碰撞系数也几乎是背风侧绝缘子整体碰撞系数的2倍;水滴碰撞系数随风速和MVD的增大而增大,且MVD对水滴碰撞系数的影响程度比风速更大;采用区域分割方式分析得到的绝缘子覆冰特性与试验结果更相符。

Serious ice accretion on insulators may cause icing flashover and lead to power-off accident of grid. Researches on the flow field and trajectories of water droplet impinging on insulator surface are of great significance to understanding the icing mechanism of insulator. We chose the aerodynamic insulator as study object. On the basis of the Lagrange method, we proposed an area-divided method of calculating droplet collision efficiency after solving the flow field and droplet trajectories around insulator. Furthermore, we experimentally investigated the effects of wind velocity and median volumetric diameter（MVD） of water droplet on water droplets impingement characteristics. It is found that there is no remarkable difference（less than 3%） between the collision efficiency on the steel cap and shed edge of aerodynamic insulator. The collision efficiency on these two areas is far higher（60%-190%） than that of windward surface. The droplet collision efficiency on windward surface is almost twice as that on leeward surface of insulator. The collision efficiency increases with the increase of wind velocity and MVD, and the influencing degree of MVD on droplet collision efficiency is more remarkable than that of wind velocity. The insulator icing characteristics by analysis with area-divided method is more consistent with that from the experimental results.