微液滴铺展动力学模型及实验验证

Dynamics model of micro-droplet spreading and experimental validation

为了研究壁面的润湿动力学行为,通过对离散化的液膜进行力学平衡方程推导,提出了一种液滴沿壁面铺展的动力学模型;模型以加速度方程表示铺展的动态变化,避免从能量角度计算复杂性的问题;利用动态接触角分析仪进行润湿实验,比较数值计算与实验结果。计算结果表明:得到的接触角随时间呈指数规律变化;液滴表面张力越小液膜越容易铺展,且所需的铺展时间越短;液滴度对铺展起阻碍作用,且缩短铺展时间;接触角动态变化规律整体一致,标准偏差在1.5°以内,说明本模型能够准确地反映液滴铺展的动态过程。

In order to study the wetting behavior of wall surface,a novel kinetic model of liquid drop spreading on wall surface was presented by the mechanical balance equations derived from discretized film. The dynamic change of spreading was expressed by acceleration equation, which breaked off the limitations of complex calculation from energetic angle. An experiment was carried out by dynamic contact angle analyzer. Results show that the contact angles change exponentially with time and the weaker the droplet surface tension is, the easier the film spreads and the shorter the time need for spreading, the droplet viscosity impedes droplet spreading, which shorten the spreading time. Compared with numerical calculation, the experimental results show that the dynamic changing regularity obtained by numerical calculation is accordance with that of by experiment with standard deviation less than 1.5°, which indicates that the model can accurately reflect the dynamics process of droplet spreadin.