Experimental Investigation On Drift Performance And Penetration Characteristics Of Air-assist Boom Sprayer

The advantage of air-assist boom spraying technology is that it can improve the atomization effect and the spray performance and reduce the droplets drift that the assist air carries the droplets to the target.Furthermore,the assist air has a tumbling effect on the target canopy,which improves the penetration and deposition performance of the droplets.At present,the study of domestic on the air-assisted boom spraying is not exhaustive,mainly concentrated in the implementation of air-assist function,integration of the machine performance and design of spray boom structure,etc.However,the research on the flow field characteristics of the air-assist boom spraying is rare.In this paper,an air-assist boom spraying performance testing system was designed through the summary of domestic and foreign literature,and diameter,penetration and drift characteristics of droplet in two-phase flow were studied based on the system,the main contents of this paper are as follows:(1)An air-assist boom spraying test system was self-designed.The test system is composed of three parts: the control part of the air curtain,the spray adjusting part and the movement control part of the spray boom,which can control the variable parameters.And it can also be used to test the droplet size,droplet drift and penetration characteristics though combining with other instruments.(2)Malvin laser particle size analyzer,Winner318 B,was combined with air-assist boom spraying and measuring system.The droplet size distribution in the spray flow field was measured,and the influence of two factors on the droplet size distribution was analyzed.The results show that the effect of pressure on spray droplet size was negatively related.The greater the spray pressure,the better the atomization,but the smaller size droplets are more easier to drift.Considering the advantage of air-assist boom spraying technology,spray pressure of 0.5 MPa is reasonable.(3)The drift characteristics of the droplets in the gas-liquid two-phase flow fieldof air-assist boom spraying were studied experimentally.The experimental results show that under the same wind velocity,the droplet drift rate decreases with the increase of assist air speed,and then increases slightly.When the assist air velocity is in 5 ~ 20m/s,the drift rate decreases linearly.The best anti-drift velocity range of assist air is 5 ~ 20m/s.When the assist air speed is too large,anti drift effect will be decreased.The best anti-drift velocity is 20m/s.Under the same wind speed,the drift mass center distance of the droplets is negatively correlated with the assist air speed.(4)The penetration characteristics of droplets in the air liquid two-phase flow field were studied by the high speed photography system.The experimental results show that the spray cone angle decreases with the increase of assist air velocity.The droplets penetration can be improved by increasing the spray.The spray pressure of0.5 MPa has a comprehensive effect of anti-drift and improving penetration.Air-assist boom spraying technology can effectively increase the penetration of the droplets.And the penetration of the droplets is proportional to the assist air velocity.When the assist air velocity is in 5 ~ 20m/s,it can be obtained to reduce the drift and enhance the penetration effect.