倾转翼无人机返航过渡段气动分析与优化

倾转翼无人机是兼有固定翼飞机和直升机优点的一种新型旋翼无人飞行器，但其过渡段的气动特性存在非线性、强耦合的特点。基于动量源方法建立了倾转翼无人机返航过渡段的数值模拟方法，经单独旋翼和Georgia-Tech模型算例验证动量源方法的准确性后，结合滑移网格技术模拟倾转翼无人机返航段并进行气动分析，通过调整旋翼转速、倾转角速度，使其定高倾转完成的时间从9.20s缩短为4.46s，在此基础上通过MATLAB不同函数拟合曲线编写入动量源，对比得到返航段走廊曲线。计算结果表明利用拟合曲线可以使其更平稳地定高倾转，使倾转翼无人机的返航过渡段受力曲线更加光滑，该方法得到的结果为控制倾转翼无人机返航过渡段的稳定性提供了理论依据。

The Aerodynamic performance analysis and optimization of the tilt-wing UAV in return transition section

Tilt-wing UAV is a new type of rotary-wing unmanned aerial vehicle which has the advantages of fixed-wing aircraft and helicopter. The aerodynamic performance of the return transition section has the characteristics of nonlinear and strong coupling. Based on the momentum source method, a unsteady numerical simulation method for the transition section of a tilt-wing UAV is established, and using individual rotor and a Georgia-Tech model to verify the accuracy of the momentum source method. Combining with the momentum source method and the sliding grid technology to simulate the return transition section of the tilt-wing UAV and analysis aerodynamic performance, by adjusting the rotor speed and tilting angular velocity, the time for completing the fixed-height tilting is shortened from 9.20s to 4.46s. On this basis, the momentum source is programmed by different fitting curves of MATLAB, and get the return section corridor curve. The simulation results show that the fitting curve can make the tilted wing aircraft flight more stable at keeping constant altitude, and the lift curve of the return transition section is smoother, and will provide a theoretical basis for controlling the stability in the return transition section of the tilt-wing UAV.