带电液滴在带电固体表面的撞击行为

Impact behavior of oppositely charged droplet and solid surfaces

实验研究带相反电荷的液滴与固体表面之间的撞击行为,探究不同液滴电荷比和不同表面电荷密度对液滴撞击行为的影响,并提出撞击过程中的电荷中和机理。研究结果表明:负电荷液滴撞击正电荷表面前,液滴底部受库仑力作用形成锥形尖端,这种锥形尖端消除了中性液滴撞击表面时产生的气泡。锥形尖端角度随电荷比和表面电荷密度增大而减小,同时带电液滴撞击表面速度随电荷比和表面电荷密度增大而增大。撞击表面瞬间,液滴内负电荷与固体表面正电荷部分中和,导致液滴接触角变小。撞击带电表面后,最大铺展直径随着液滴电荷比和表面电荷密度增大而增大,接触时间和最大反冲高度随着液滴电荷比增大而增大,随着表面电荷密度增大而减小。

The impact dynamics between oppositely charged droplets and solid surfaces was explored through experiments and the effect of charge conditions on impact dynamics was obtained.The mechanism of action during the impact process was proposed.The results show a conical tip contact between droplets and solid surfaces.With higher charge densities of droplets and solid surfaces,the conical tip angles get larger.Such a conical tip contact can eliminate the impacting bubbles between neutral droplets and solid surfaces.In the case of charged droplets impacting a charged surface,the negative charge in the droplet and the positive charge on the surface are partially neutralized.Charge neutralization leads to smaller droplet contact angles.The maximum spread width increases with the increase of droplet charge density and surface charge density.The contact time and recoil height increase with the increase of droplet charge density and decrease with the increase of surface charge density.