Abstract:Because of wind stress, the movement trajectory of fog droplet in space was changed, and the deposition distribution of fog droplets on the target surface was changed. In order to study the effect of different factors on this phenomenon, a test of droplet deposition distribution in closed silo was designed. The variables were the transverse wind at different speeds (1m/s, 2m/s and 3m/s), spray height (30cm, 40cm and 50cm) and spray pressure (0.4MPa, 0.6MPa and 0.8MPa). Based on the experimental measurement results of deposition distribution, a bimodal distribution mathematical model based on normal distribution probability density function was established. The physical significance of each coefficient in the model was also explained, and the influence of various horizontal factors on the coefficients in bimodal distribution and influence relationship of each horizontal factor on the coefficient in bimodal distribution were analyzed. This mathematical model can more systematically express the relationship between deposition range and deposition quality. The variation law of deposition parameter k1 was opposite to k2. With the increase of spray height, spray pressure and cross wind speed, k1 was decreased while k2 was increased, and deposition shifted from the first peak distribution to the second peak distribution. The two position parameters μ1 and μ2 of the bimodal distribution had the same variation trend, both increasing with the increase of wind speed and height, and decreasing with the increase of spray pressure. Therefore, increasing the spray pressure can reduce the center drift distance. The range of the first and second peak distributions (scale parameters σ1 and σ2) were increased with the increase of spray height and wind speed, and the deposition distribution was more dispersed. Increasing the spray pressure can effectively reduce the deposition dispersion of the first peak, but it had no effect on the distribution of the second peak. This study investigated the effects of different intensity of transverse wind and spray height and pressure on droplet drift deposition distribution, providing a reference for optimizing pesticide spray technology and improved droplet resistance to drift.
