不同电场波形下液滴极化变形规律研究

Investigation on the law of droplet polarization and deformation under different electrical waveforms

为了深入研究电场波形对液滴变形的影响,基于相场方法,建立了互不相融两流体中液滴变形的仿真模型,实现了流场和电场的耦合。模拟研究了直流脉冲、半正弦波、半三角波和半锯齿波4种电场波形对液滴变形的影响。模拟结果显示,液滴变形度曲线与电场波形相似,且液滴振荡变形的频率与电场频率相同。此外,还研究了以上4种波形电场的场强幅值和频率对液滴变形度的影响。结果显示,电场的均方根RMS越高,液滴变形度越大;随着场强幅值的增加,4种波形条件下液滴变形度近似呈指数增加;随着频率的增加,直流脉冲和半正弦波电场条件下液滴变形度呈先增加后减小的趋势,存在最佳频率40 Hz,半三角波和半锯齿波电场条件下液滴变形度近似呈线性减小。

In order to investigate the influence of electrical waveforms on the droplet deformation, a simulation model in two immiscible fluids was established with the phase field method. The coupling effects of flow field and electric field were achieved. The effects of four kinds of electrical waveforms （e.g. pulsed DC, half-sinusodial, half-triangular and half-sawtooth waveforms） on droplet deformation were simulated and studied. The simulation results show that the droplet deformation curve is similar to that of the electrical waveforms, and the droplet oscillation frequency is the same as the electric field frequency. In addition, the effects of electrical intensity amplitudes and frequencies on the droplet deformation are investigated. The results show that the higher the root mean square （RMS） values of the electric field, the larger the deforming extent of the droplet. With increasing electrical intensities, the droplet deformation of all waveforms increases exponentially. With increasing electrical frequencies, the deformation of droplet increases first and then decreases under pulsed DC and half-sinusodial electric fields. The optimum frequency is 40 Hz. However, the droplet deformation decreases linearly under half-triangular and half-sinusodial electric fields.