增升增效倾转翼农用植保无人机的设计与仿真

【目的】为满足无人机田间作业既具有旋翼机灵活起降的功能又具备固定翼长航时的特征，设计了一种X字布局的旋翼、固定翼混合结构且具有倾转功能的新型农用植保无人机。【方法】根据农田喷施作业的负载动力要求对无人机的增升装置进行了翼型和参数的设计。利用SolidWorks软件搭建了植保无人机的机体结构，使用Fluent软件结合Spalart-Allmaras湍流模型，对植保无人机增升增速参数进行了气动仿真分析。【结果】仿真试验发现，升力系数与迎角和空速呈正相关，其中，迎角从4°至6°变化时的影响较为强烈；迎角对应5°～30°前倾角时，升力系数达到0.81。在5 m/s的空速下，迎角和前倾角的关系几乎呈线性分布，机头前倾即可增大升力系数，进而增加有效负载，使得整体植保无人机的作业效率得到提升。【结论】本文为设计倾转翼植保无人机提供了理论依据，也为植保无人机延长续航时间、提升作业效率打开了新思路。

Design and simulation of agricultural plant protection UAV with tilt-rotor of increased lift and efficiency

Objective In order to meet the field operation requirements, the UAV needs not only a rotor with the function of flexible take-off and landing, but also fixed wings with the characteristics of long endurance. A new agricultural plant protection UAV with X-shaped rotor and fixed wing hybrid structure as well as tilting function was designed. Method According to the load dynamic requirements of farmland spraying operation, the airfoil and parameters of the lifting device of UAV were designed. The body structure of the plant protection UAV was built using SolidWorks software. The aerodynamic simulation analysis of the increasing lift and speed parameters of the plant protection UAV was carried out using the Fluent software and Spalart-Allmaras turbulence model. Result The simulation results showed that the lift coefficient was positively correlated with the attack angle and the airspeed, and the influence of the attack angle was stronger when it changed from 4° to 6°. The lift coefficient reached 0.81 when the attack angle corresponded to the 5°-30° tilt angle. At the airspeed of 5 m/s, the relationship between the attack angle and the tilt angle almost showed linear distribution. Forward tilt of the nose could increase the lift coefficient, and then increase the payload, so that the overall operational efficiency of plant protection UAV was improved.Conclusion The study provides a basis for the design of plant protection UAV with tilt wing, and also offers a new idea for improving the endurance time and operation efficiency of plant protection UAV.