果园风送静电喷头设计与试验

Design and experiment of air-assisted electrostatic nozzle for orchard

[目的]针对雾滴在叶背面覆盖密度低的问题,设计了一种风送静电喷头。[方法]根据感应充电模型,同时进行理论计算,从而设计出电极及电极帽的尺寸。电极设计成锥形电极,开角为80°,高10 mm,厚2 mm,材料为铜,具有高导电性;电极帽设计成仿锥形,防止电极被药液腐蚀,材料选用环氧树脂制作,可提高介电常数,增大感应充电电场电荷。并对喷头进行了3个方面的性能试验,包括荷质比测量、静电雾滴覆盖密度对比试验和田间验证试验。[结果]荷质比测量表明:雾滴在喷头处的最大荷质比为1.167 m C·kg-1,并且距离喷头1 m处的雾滴仍然带电。雾滴覆盖密度对比试验表明:静电及喷雾距离对正、背面覆盖密度影响显著,在喷雾距离1～2 m内,背面覆盖密度相对增幅可达70%以上。田间验证试验证明:静电作用同时作用了叶片正、背沉积;风机转速对荷质比的影响与对叶片正、背沉积量的影响结果一致。[结论]研究证明该静电喷头具有明显的静电喷雾效果,可为果园风送静电喷头的设计与效果检验提供参考。

[Objectives]In view of the low density of the fog droplet on the back of the leaf,a kind of air-assisted electrostatic nozzle was designed.[Methods]According to the induction charging model,the theoretical calculation was carried out at the same time,so as to design the size of electrode and electrode cap.Design of electrode tapered electrode opening angle of 80 degrees,high 10 mm,thickness 2 mm,material was copper,with high conductivity.The electrode cap was designed to be conical to prevent the electrode from being corroded by the liquid.Electrode cap material selection of epoxy resin,can improve the dielectric constant increase induction charging electric charge.In this paper,the experiment of the nozzle was carried out in three aspects:the charge mass ratio measurement,the droplet coverage density contrast test and field test.[Results]The charge mass ratio measurement test showed that the droplets in the nozzle at the maximum charge mass ratio was 1.167 mC·kg^-1,and the droplets 1 m away from the nozzle were still electrified.The droplet coverage density contrast experiment showed that the static and the spray distance was significant on the cover density.In the spray distance 1-2 m,the droplet coverage density on the back of paper card relative increase could reach above 70%.The field test proved that the electrostatic action simultaneously acted on the deposition of leaves’front and back.The influence of the speed of the fan on the charge mass ratio was consistent with the effect on the deposition of leaves’front and back.[Conclusions]The electrostatic nozzle had the obvious effect of actual spray.The paper can provide a reference for the design and effect test of the air-assisted electrostatic nozzle in the orchard.