基于非定常动量源方法倾转翼无人机起飞过渡模式气动分析

The aerodynamic analysis of the transition mode for a tilting wing UAV Based on the unsteady momentum source method

摘要:

倾转翼无人机作为倾转动力式垂直起降无人机，在过渡模式下，旋翼滑流与前方来流相互耦合，无人机的受力呈现出极强的非定常性与非线性特点。本文采用非定常动量源方法，通过在动态变化的扇形区域中添加动量源项模拟真实旋翼，并结合滑移网格技术实现连续倾转过程。通过分析无旋翼、固定倾转角度及连续倾转三种状态下的计算结果，研究不同来流速度与倾转速度对机翼-旋翼气动特性的影响，为倾转翼无人机在起飞过渡模式下设计合理的倾转方式提供参考。研究发现：旋翼滑流可有效延缓失速迎角；固定倾转角与连续倾转计算结果存在显著差异，表明连续倾转过程具有不可忽略的非定常气动特性；低速飞行时，较快的倾转速度有利于提高升力；倾转翼无人机在过渡模式下需通过实时调节旋翼转速以维持飞行姿态稳定。

Abstract:

The Tilting Wing UAV is a type of vertical take-off and landing (VTOL) unmanned aerial vehicle, during the transition mode, the interaction between the rotor slipstream and the freestream flow affects the tilting wing, creating strong unsteady aerodynamic disturbances that significantly influence the UAV's performance. This study used the unsteady rotor momentum source method, simulate a real rotor by adding the momentum source in a dynamically changing sector areas. Using the sliding mesh technique, continuous tilting is simulated. Through numerical analysis of non-rotor, fixed-tilt, and continuous-tilting configurations, studying the influence of freestream velocity and tilting rate on the aerodynamic interaction between wings and rotors, to provide a reference for the design of a reasonable tilting mode for tilting wing UAV in take-off transition mode The results show: rotor slipstream can effectively delay the stall angle of attack; Significant discrepancies between the computational results of fixed tilt angles and continuous tilting highlight the non-negligible unsteady aerodynamic characteristics inherent in the continuous tilting process; During low-speed flight, a faster tilting speed is beneficial for increasing lift. In transition mode, The tilting wing UAV require real-time adjustment of rotor speed to maintain flight attitude stability.