翼尖铰接复合飞行器动力学特性研究

航空飞行器通过翼尖铰接机构复合飞行时的气动耦合效应，会造成飞机产生不同于其单独飞行时的动力学特性，出现复合飞行安全问题。为研究翼尖铰接复合飞行器的动力学特性，使用Newton-Euler方法和Robberson-Wittenburg方法建立了双机组成的翼尖铰接复合飞行器多刚体系统整体和内部的7自由度非线性动力学和运动学方程组。在气动准定常假设下建立双机复合系统非耦合气动力表达式，基于CFD方法开展复合飞行器系统的三维实体建模和非结构网格划分工作，获取复合飞行器系统的气动力数据。搭建动力学仿真平台，开展准配平方案和全配平方案下的动力学仿真。仿真结果表明:准配平方案下飞行器无法持续稳定飞行，而全配平方案下复合飞行器系统各运动参数在仿真时间内始终趋于稳定。在全配平方案下，使用小扰动假设的非解耦线性化方法重新整理7自由度动力学方程组，研究复合飞行器系统运动模态的特征值中出现的2个发散新模态，根据对应的特征向量发现2个发散模态分别由相对滚转角度和角速度主导，同时也比较分析了其他运动模态相比单机飞行时的特性变化规律。 

Dynamic characteristics of wingtip-jointed composite aircraft

The aerodynamic coupling effect of the composite flight of aircraft via wingtip-jointed structure determines the dynamic characteristics different from those of its independent flight, where safety risks might exist. In order to investigate the dynamic characteristics of the wingtip-jointed composite aircraft, the Newton-Euler method and Robberson-Wittenburg method are used to derive the 7-degree-of-freedom nonlinear dynamics and kinematics equations of the multi-body system of the wingtip-jointed composite aircraft composed of two aircraft. Under the aerodynamic quasi-steady assumption, uncoupling aerodynamic force formula for two-aircraft composite system is established, and the composite aircraft system's three-dimensional modeling and unstructured meshing are further carried out based on the CFD method to obtain the aerodynamic data. The dynamic simulation platform is built, and the dynamic simulations under the quasi-trimming strategy and the full-trimming strategy are carried out on the dynamic simulation platform. The result proves that the aircraft cannot continue to fly stably under the quasi-trimming strategy, while the motion parameters of the composite system under the full-trimming strategy always tend to be stable. Under the full-trimming strategy, the decoupling linearization method using small disturbance hypothesis is used to rearrange the terms of the 7-degree-of-freedom dynamic equations, and study the two new divergent eigenvectors in the eigenvalues of the composite system motion modes, which shows that the two divergent modes are dominated by the relative roll angle and angular velocity. Meanwhile, the characteristics of other modes compared with the single-plane flight are summarized and analyzed.