多旋翼无人机旋翼下方风场对航空喷施雾滴沉积的影响

Effect of Wind Field below Rotor on Distribution of Aerial Spraying Droplet Deposition by Using Multi-rotor UAV

风场是影响航空喷施雾滴沉积分布特性的重要因素之一。为了揭示多旋翼无人机旋翼下方风场对雾滴沉积分布的影响机理,通过无人机旋翼风场测量系统测量多旋翼电动无人机旋翼下方的风场分布,同时结合航空喷施雾滴在水稻冠层的沉积情况,分析旋翼下方X、Y、Z 3个方向的风场对雾滴沉积分布的影响,并对试验结果进行了方差分析和回归分析。结果表明:在无人机旋翼下方3向风场中,X和Y向风速对有效喷幅区内雾滴沉积量的影响不显著,Z向风速的影响极显著;X向风速对有效喷幅区内雾滴沉积穿透性的影响不显著,Y和Z向风速的影响分别为显著和极显著;X和Y向风速对雾滴沉积飘移的影响均不显著,Z向风场的影响显著;且当水平方向上X、Y向风速峰值越小、垂直方向上Z向风速峰值越大时,雾滴沉积均匀性越好,最佳值达到36.44%。另外,有效喷幅区内雾滴沉积量与因素Z向风速之间的回归模型及有效喷幅区内雾滴沉积穿透性与因素Y和Z向风速之间的回归模型的决定系数R^2分别为0.868和0.842,表明模型可以为实际作业提供指导。

Currently,studies about aerial spraying application of agricultural unmanned aerial vehicle（ UAV） in China mainly focus on the effect of aerial spraying operation parameters（ flight height and flight velocity） of single-rotor UAV on droplet deposition distribution. In fact,the main factor that affects the droplet deposition distribution of aerial spraying is the wind field below the UAV rotor,which is made up of wind field generated by rotating rotor and wind field of external environment. The effect of wind field below agricultural UAV rotor needs to be taken into account in the study of the distribution regularity of aerial spraying droplet deposition. Moreover,the wind field generated by multi-rotor electric UAV during operation is the result of multiple rotor interaction. The distribution of wind field and the effect of wind field on the distribution regularity of droplet deposition are different with single-rotor UAV. In order to reveal the impact mechanism of droplet deposition distribution by the wind field below the multi-rotor electric UAV rotor,wind field distribution below multi-rotor electric UAV was measured by using a wireless wind speed sensor network measurement system for unmanned helicopter,and the impact on the distribution of droplet deposition was analyzed by the wind field in X,Y and Z directions below rotorcombined with the condition of aerial spraying droplets deposition in rice canopy,and the regression model was established by making the variance analysis and regression analysis of experiment results. The results showed that the trends of droplet deposition in the plant layers were basically similar,the deposition amount of droplet was decreased from upper layer to lower layer. Because of the different operating parameters,the distribution of wind field below rotor in each experiment were different,but the value of wind speed in different directions showed the decreasing trend in Z,Y and X directions. Among the three directions wind field below multi-rotor electric UAV rotor,the wind field in X and Y directions had no significant impact on droplet deposition in the effective spray area,the wind field in Z direction had an extremely significant impact on droplet deposition in the effective spray area,the Sig. value was less than 0. 001. The wind field in X direction had no significant impact on droplet deposition penetration in the effective spray area,the wind field in Y direction had a significant impact and the wind field in Z direction had an extremely significant impact on droplet deposition penetration in the effective spray area,the corresponding Sig. values were 0. 037 and less than 0. 001. The wind field in X and Y directions had no significant impact on droplet drift,the wind field in Z direction had a significant impact on droplet drift,the Sig. value was 0. 036. Furthermore,the horizontal wind field in X and Y directions and the vertical wind field in Z direction all affected the deposition uniformity in the effective spray area. With the smaller value of horizontal wind field in X and Y directions and the larger value of vertical wind field in Z direction,the uniformity of droplet deposition was better,the best value reached 36. 44%. In addition,the corresponding determination coefficient R^2 of the regression model between droplet deposition in effective spray area and the wind speed in Z direction as well as between droplet deposition penetration in effective spray area and the wind speed in Y and Z directions were 0. 868 and 0. 842,respectively,and these models can provide guidance for the practical application. The result revealed the effect on the distribution of aviation spraying droplet deposition by the wind field below the multi-rotor UAV rotor,and it had an important guiding significance in the practical application such as reducing liquid drift in aerial spraying and improving the utilization rate of pesticide.