高压脉冲负电晕荷电喷雾试验研究

Experimental Study on Electrostatic Spraying of Negative High-voltage Pulse Corona Charge

为减少化学农药带来的污染,采用了荷电喷雾新技术。首先对负高压脉冲电晕荷电机理进行了理论分析,再用网状目标法通过调节电压、极距、电极直径、电极数目等参数进行电晕荷电试验,比较各因素对电晕放电伏-安特性影响及荷电后雾化效果;测量不同电压下雾滴的索太尔直径;并用高速摄影拍摄雾滴带电射流破碎时的状态,得到射流破碎时的雾滴形状。理论分析和试验结果表明,电压越高,雾滴谱较窄,雾滴粒径变细,均匀度越高;揭示了不同影响因素下的雾滴荷电特性,为负高压脉冲电晕荷电喷雾技术的应用和设计提供了理论基础和试验数据。

In order that the electrostatic spraying equipment may be worked out as a high efficient corona charging system for the spray droplets, the mechanism of charging fine droplets and negative high-voltage pulse corona charge system are analyzed theoretically. The method of mesh target to measure the charge to mass ratio is introduced and the indoor experimental system is set up. Several kinds of electrostatic electrode have been designed. Experimental investigation was performed for electrostatic spraying under annular electrode configuration. The main factors which affect the spray charge, such as, the voltage, the construction and dimension of the corona electrode, the distance between the center of electrode ring and the spraying nozzle, the curvature radius of electrode, electrode number were analyzed. Comparison of these parameters influencing current-voltage characteristics of corona discharge and atomization effect under the various experimental conditions was discussed in this paper. In addition, the shape of the charged droplet was obtained by using high speed photograph to observe the state of charged broken injection. Both experimental results and theoretical analyses to the electrostatic spraying show the electrostatic effect in spraying process and how the charging voltage affects the atomization. This research demonstrates that effect of charging voltage on droplet size （VMD）, charge of the droplet and distribution of droplets is obvious. The distributions of droplet diameter exhibit different characteristics. Increases in the voltage of the electrode will lead to rise of the uniformity of the droplets and the droplets table is narrower, the droplet diameter is smaller, deposit amount and the atomization quality is better. There still exists the droplet charging amount far away from the spraying nozzle. This paper provides a reliable theoretical foundation and the relevant technical data for the design and application for the negative high-voltage pulse corona charge spraying equipment.