多翼单臂纵列式电动无人机旋翼间距优化及能耗试验

针对现代农业航空技术的发展对电动多旋翼农用无人机的载荷能力、持续作业能力、作业效率提出更高的要求，而目前电动多旋翼植保无人机存在续航时间短、载质量小、作业效率低等问题，该文通过试验测试平台，首先对共轴式双旋翼进行不同纵向间距下的升力性能及能耗测试，分析纵向间距对双旋翼升力的影响规律，根据分析结果，针对纵列式双旋翼进行升力随横向间距的变化规律研究，得出横向间距比等于1.8为双旋翼纵列式方式的最优横向间距比。随后对不同尺寸纵列式双旋翼和纵列式多旋翼升力随横向间距比的变化规律进行测试，验证最优横向间距比1.8的普遍适用性。最后，对多旋翼单机臂结构六轴十二旋翼纵列式布局无人机的综合性能参数进行优化分析，并对平面式、纵列式布局方式下的六轴十二旋翼无人机进行飞行试验，验证旋翼间距的优化结果。优化分析结果表明，横向间距比均分别在最优化条件下时，纵列式和平面式布局的升力远高于共轴式布局。与纵列式布局相比，平面式布局机型升力差别不大，但机身尺寸增加38.70%。飞行试验结果表明，在相同负载下,相对于优化后的纵列式机型,平面式机型在单位时间内悬停功率仅减小0.062%，而机身质量增加6.8%。该研究在保证无人机能效的前提下，通过改变旋翼间的相对位置，对多旋翼单机臂结构电动无人机的旋翼间距进行优化，从而优化机身尺寸及质量，改善多翼单臂结构无人机的气动特性，降低惯性，提升有效负载能力，从而提升整机性能。

Optimization of rotor spacing and energy consumption test for multi-rotor single arm tandem electric UAV

Along with the continuous development of agricultural aviation application technology, an agricultural unmanned aerial vehicle (UAV) is widely used in modern agricultural production, which is the operation platform for implementing agricultural aviation technology. Due to the characteristics of simple operation, simple structure, easy maintenance and low cost, electric multi-rotor UAV is widely used in the field of agricultural aviation. However, it has the problems of small load capacity, short continuous operation time, low operation efficiency, etc. The multi-rotor single-arm tandem structure can effectively improve the load capacity and operation capacity of the electric UAV, but the structure will lead to the increase of the size and mass of the whole machine and reduce the effective utilization rate of energy, which still needs to be optimized and improved. Rotor spacing affects the overall performance of multi-rotor single-arm tandem electric UAV, but the influence of different rotor spacing on rotor lift of multi-rotor single-arm structure has not been studied. In this paper, by setting up a test platform and taking power consumption (P) and lift (F) as test indexes, the rotors with different spacing were tested, and the optimal spacing ratio between tandem rotors was analyzed and determined. The optimal spacing ratio was verified by theoretical analysis and flight test of solid aircraft. The lift performance and energy consumption of coaxial and tandem twin rotors at different spacing were tested. The results showed that the longitudinal spacing ratio had no effect on the lift performance, while the lateral spacing ratio had an effect on the lift performance. In order to further determine the optimal lateral spacing ratio, the variation law of rotor lift with lateral spacing ratio under the double rotor tandem arrangement was tested. When the lateral spacing ratio was less than 1.8, the lower rotor lift increased with the increase of lateral spacing ratio under the same power consumption. When the lateral spacing ratio was greater than 1.8, the lift of the lower rotor tended to be stable, and the average value of the lower rotor lift relative to the loss percentage of the isolated rotor was stable within 0.70%. When the lateral spacing ratio was equal to 1.8, the average loss percentage of the rotor lift under the tandem layout was 0.66% relative to the isolated rotor lift under different power consumption. At this time, the lower rotor lift is basically the same as the isolated rotor lift, thus determining that the optimal spacing ratio of the tandem double rotor was equal to 1.8. Secondly, by testing the variation of the lift force of two rotors with different sizes and the rotor lift force with the lateral spacing ratio under the tandem layout of multiple rotors, it was concluded that 1.8 was suitable for the tandem layout mechanism with different sizes and number of rotors. In order to validate the optimal effect of the lateral spacing ratio of 1.8 on the rotor spacing of the multi-rotor single-arm tandem electric UAV, this paper compared and analyzed the performance parameters of planar and tandem aircraft of six-axis 12-rotor UAV with multi-rotor single-arm structure. The results showed that compared with the tandem model with lateral spacing ratio 1.8, the fuselage size of the planar model increases by 38.70%, while the lift difference between the two is only 1.52%. Through flight tests, the results showed that under the same load, the hovering power per unit time of the planar model decreased by only 0.06%, while the fuselage mass increased by 6.82% compared with the optimized tandem model, the fuselage size increased by 38.7%. This paper studied the optimal rotor spacing of multi-rotor single-arm electric UAV. On the premise of ensuring the energy efficiency of the UAV, the rotor spacing of the multi-rotor single-arm structure electric UAV is optimized by changing the relative positions between the rotors, so as to optimize the fuselage size and mass, improve the aerodynamic characteristics of the multi-rotor single-arm structure UAV, reduce inertia, enhance payload capacity, and thus improve the overall performance.