双毛细管静电雾化模式及雾化特性实验研究

Experimental investigation on electrostatic atomization mode and atomization characteristics of double capillaries

通过可视化实验研究了双毛细管静电雾化现象。以无水乙醇为介质,使用激光粒子图像分析测试系统(particle/droplet image analysis, PDIA)、粒子图像测速法(particle image velocimetry, PIV)和高速摄影方法测量和分析了雾化模式和液滴的粒径分布、径向与轴向速度分布和锥角变化。结果表明:当改变流量与电压时,静电雾化呈现滴状、纺锤状、脉动射流、稳定锥射流、多股射流等多种雾化模式;因流量与电压的变化导致单位表面荷电量变化,进而变化了表面张力使得各处粒径大小发生变化,发现双毛细管雾化粒径空间分布规律呈近似M型,雾化状态越稳定粒径波动越小,且粒径远小于单毛细管雾化粒径以及雾化范围更广;液滴径向速度分布呈线性,雾化状态越稳定线性关系越强,液滴与毛细管末端距离对径向速度近无影响,流量对轴向速度影响远大于电压。液桥锥角在稳定锥射流模式最小,脉动模式锥角最大。

The electrostatic atomization phenomenon of double capillaries was visually investigated. Absolute ethanol was used as the experimental medium. Atomization mode, the particle size distribution, radial and axial velocity distribution and the variation of the atomizing cone angle were measured and analyzed by using PIV, PDIA and high-speed photography respectively. Results showed that changing the flow and voltage can make the electric atomization mode present varieties such as drops, spindles, pulsating jets, stable cone jets, and multiple jets. The change of flow and voltage leads to the change of unit surface charge, which further changes the surface tension and makes the particle size change. And the particle size distribution is approximately M-shaped. The more stable the atomization state, the smaller the particle size fluctuation.The partical size of the double-capillaries atomization is much smaller than that of the single-capillary atomization and the atomization range is wider. The radial velocity distribution of the droplet is linear. The more stable the atomization state, the better linearity. The distance between the droplet and the end of the capillary has no effect on the radial velocity, and the flow rate affects the axial velocity much more than the voltage. The atomizing cone angle of the liquid bridge is the smallest in the steady cone jet mode and reaches maximum in the pulsation mode.