不同侧风和静电电压对静电喷雾飘移的影响

Influence of lateral wind and electrostatic voltage on spray drift of electrostatic sprayer

为研究不同侧风和静电电压对静电喷雾雾滴飘移的影响规律,设计不同侧风(恒速风1、2、4 m/s及0~4 m/s变化的模拟自然风)及静电电压(0,2,4,6,8 k V),进行喷杆式静电喷雾机的雾滴飘移试验,测定不同静电电压下的雾滴粒径与荷质比,并对比分析雾滴飘移质量中心距和飘失率。结果表明:随着静电电压的增大,雾滴粒径减小,雾滴荷质比增大,0~8 k V电压下电极干燥和电极打湿对雾滴荷质比没有显著影响。在侧风风速为1 m/s时,0~8 k V静电喷雾的雾滴飘移中心距小于0.55 m,雾滴飘失率低于15%。在侧风风速2 m/s时,非静电喷雾的雾滴飘失率为11.9%,6~8 k V静电喷雾的雾滴飘失率超过20%,其中静电电压8 k V的雾滴飘失率(23.9%)比非静电喷雾增加100.8%。在侧风风速4 m/s时,4~8 k V静电喷雾的雾滴飘移中心距在0.9 m以上,雾滴飘失率在30%以上,其中静电电压8 k V下的雾滴飘移中心距为967.2 mm比非静电喷雾下增加了13.7%,雾滴飘失率为35.4%比非静电喷雾下增加了59.5%。相同静电电压下,2 m/s的恒速风和0~4 m/s变化的模拟自然风之间对雾滴飘失率无显著差异。该研究为优化喷雾技术参数和提高雾滴抗飘移的能力提供参考。

In order to study the influence of lateral wind and electrostatic voltage on spray drift of an electrostatic sprayer, the measurement of spray drift was performed through a self-propelled orchard sprayer with a spray boom. The spray boom was equipped with an electrostatic spraying system. The effects of lateral wind (1, 2, 4 m/s constant speed wind and 0-4 m/s non-constant speed wind) and electrostatic voltage (0, 2, 4, 6 and 8 kV) on spray drift were evaluated with the spray pressure at 0.5 MPa by analyzing the spray drift percentage and droplet drift distance. Fan blower provided no boundary planar wind in the form of 1.5 m × 1.5 m. The horizontal distance between the fan and nozzle was 1.0 m. An anemometer was used for wind speed calibration at the nozzle position during the experiment. Droplet size and charge-to-mass ratio were measured under different electrostatic voltages. The spray charge-mass was calculated using the ratio data of spray cloud currently acquired by a system consisted of a Faraday’s cage, charge–voltage convertor and data acquisition. The results showed that the droplet size decreased as the electrostatic voltage of constant wind increased, and the charge-to-mass ratio increased as the electrostatic voltage increased and then tended to be stable. The charge-to-mass ratio was not significantly different between dry and wet electrodes at 0-8 k V electrostatic voltages. Electrostatic voltage and lateral wind both had significant impact on the droplet drift distance and spray drift percentage and their interaction was significant (P<0.05). Increasing lateral wind speed of constant wind and electrostatic voltage could improve the spray drift. At the same lateral wind velocity, the droplet drift distance and spray drift percentage still were significantly different (P<0.05) between 6 and 8 kV voltages. When the lateral wind speed was 1 m/s, the droplet drift distance of electrostatic spraying was 0.55 m or less, and the droplet drift percentage was below 15%. When the lateral wind speed was 2 m/s, the droplet drift percentage of 6-8 kV electrostatic spraying was more than 20%, especially the droplet drift percentage of 8 kV electrostatic spraying was 23.9%, which increased by 100.8% compared to that of non-electrostatic spraying. When the lateral wind speed of 4 m/s, the droplet drift distance of 4-8 kV electrostatic spraying was more than 0.9 m, the droplet drift percentage was more than 30%, especially the droplet drift distance and droplet drift percentage of 8 kV electrostatic spraying were 967.2 mm and 35.4%, which increased by 13.7% and 59.5% respectively compared to those of non-electrostatic spraying. It indicated that electrostatic spraying is suitable for working under low wind speed even 0. It suggested that when spraying is conducted under the high wind speed, the low voltage spraying or non-electrostatic spraying should be used. The results can provide a guide for the spray technology parameters optimization, so as to improve the ability of droplet anti-drift.