Analysis of hydraulic nozzles for pesticide applications on atomization and droplets distribution characteristics

Hydraulic nozzles are widely used among many kinds of spray nozzles due to their large atomization volume, energy saving, simple structure, economical practicality. It’s important to study the atomization and deposition characteristics of hydraulic nozzles for optimizing pesticide application performance. In order to determine the influence of hydraulic nozzles on its atomization and deposition characteristics, droplet size, velocity and deposition distribution of 6 kinds of hydraulic nozzles (standard flat fan XR 110-015, anti-drift flat fan DG 110-015, air-induction flat fan AIXR 110-015, air-induction flat fan AI 110-015, hollow cone TXA 80-015 and air-induction hollow cone AITXA 80-015) were tested. The results showed that droplet sizes of all nozzles decreased with increasing spray pressure with little difference in volume median diameter (D_v0.5) between fine (XR 110-015) and medium droplet nozzles (DG 110-015) under different spray pressures. In contrast, coarse (AIXR 110-015) and extremely coarse droplet nozzles (AI 110-015 and AITXA 80-015) were more sensitive to spray pressure, and the D_v0.5 of droplet decreased dramatically with increasing spray pressure. Droplets velocity was mainly determined by nozzles type and spray pressure has little effect on droplet velocity, in which case the same nozzle at different spray pressures has similar droplet velocity trends. Under the same spray pressure, the average velocity (V_avg) of fine droplet nozzle was greater than its volume median droplet velocity (V_v0.5), while with the increase of the droplet diameter, the V_v0.5 of nozzles exceeded its V_avg. The flow rates of all nozzles were quite close but lower than its nominal flow rates, and the loss rates of nozzles ranged from 7.82% to 9.75%. Spray pressure has little effect on droplet distribution uniformity of DG 110-015, XR 110-015 and AIXR 110-015, but a higher pressure was beneficial for the uniformity distribution of AITXA 80-015 and TXA 80-015. This study can provide theoretical guidance and technical reference for the selection of hydraulic nozzles and the optimization of pesticide application parameters.