Experimental Study On Atomization Characteristics Of Non-load Air-assisted Electrostatic Spray

In the hilly and mountainous areas of Southern China,limited by the complexity of the orchard,Orchard spraying is still dominated by non-loaded handheld spray machines.In the process of operation,the droplets penetrate the fruit tree canopy with weak penetration,poor adhesion,and low pesticide utilization.It hinders the timeliness and effectiveness of pest control.Research on efficient and portable non-loaded handheld spray technology is particularly important for the management of plant protection in southern orchards.However,the operating mechanism of the non-load air-assisted electrostatic spray technology has not been sure yet,and the atomization performance of the droplets lacks effective and accurate test data.Therefore,in this paper,PDA（Phase Doppler Anemometry）is used to carry out the experimental study on the atomization characteristics of non-load air-assisted electrostatic spray.The main research contents and conclusions are as follows:（1）Designed and built a non-loaded air-assisted electrostatic spray test platform,which is divided into two parts:PDA measuring system and air-assisted contact charged electrostatic spray system.（2）Around the four factors of charging voltage,spray pressure,measuring distance,and wind speed of the fan,a single factor test was carried out using PDA to measure the droplet size,and the test results showed that:a.Under the conditions of wind speed 0m/s,measuring distance 400mm,charging voltage 0～12k V,spray pressure 0.4MPa～0.8MPa,spray pressure and charging voltage are negatively correlated with D₃₀,and the significant ratio of spray pressure The larger the charging voltage;the greater the spray pressure,the smaller the characteristic droplet size and divergence index RS（Relative Span）of the droplet,and the larger the V100,indicating that the uniformity of the droplet size is more ideal,and the relative range of the droplet size is more concentrated;the effect of the charging voltage on D₃₀ is graded.For the droplets of small particle size,the effect of the charging voltage on the particle size changes relatively small,and the effect of the droplets with large particle size is relatively large,when the spray pressure is At 0.8MPa,as the charging voltage increases,the smaller the characteristic particle size,the larger the droplet divergence index RS,indicating that the uniformity of the droplet size is more ideal,and the droplet size range is more dispersed.b.Under the condition of spray pressure 0.8MPa,wind speed of air outlet 0m/s,charging voltage 0～12k V,measuring distance 200～800mm,the measuring distance is positively correlated with D₃₀,the significance of the measuring distance is greater than the charging voltage;when the charging voltage is 0k V,with the increase of the measurement distance,the larger the characteristic diameter of the droplet and the droplet divergence index RS,the smaller the V100,indicating that the uniformity of the droplet size is not ideal,and the relative size of the droplet size The range is more divergent;under the condition of measuring distance of 200～600m,the charging voltage is negatively correlated with D₃₀,and at the measuring distance of 800mm,the charging voltage is positively correlated with D₃₀.The larger the electrical voltage,the smaller the divergence index RS of the droplets and the larger the V100,the more dispersed the droplet size.c.Under the conditions of spray pressure 0.6MPa,measuring distance 600mm,charging voltage 0～12k V,wind speed 0～11m/s,wind speed is negatively correlated with D₃₀,and charging voltage is positively correlated with D₃₀.The saliency of voltage is more significant than the effect of wind speed;the larger the wind speed,the smaller the characteristic particle size,indicating that the uniformity of the droplet size is more ideal.The larger the charging voltage,the smaller the droplet divergence index RS and the larger the V100,indicating that the relative range of droplet size diverges.（3）Using Design-Expert 12 to carry out the response surface test,the results show that the degree of influence of the three factors in the fitting equation on D₃₀,in order from strong to weak,is:spray pressure,measured distance,charged voltage;in interactive analysis,two Factors affect the sequence of D₃₀,from strong to weak,in order:spray pressure and measuring distance,spray pressure and charging voltage,charging voltage and measuring distance.