Z型翼变体飞机的纵向多体动力学特性

机翼变形时,变体飞机的翼面积、惯性特性、全机焦点和重心位置等均会发生较大的变化,从而引起飞机的动态特性也随之改变。为此对机翼变形过程中的Z型翼变体飞机进行了纵向多体动力学建模仿真;推导了变形过程中变体飞机的六自由度非线性动力学方程,并通过简化得到了解耦后的纵向动力学方程。机翼折叠动态过程的气动特性数值模拟结果表明,不同折叠角速度下飞机的气动力相差不大。在机翼折叠角速度较小且忽略非定常气动效应的情况下,采用气动力准定常假设对变形过程中不同机翼折叠角速度下变体飞机的纵向响应进行了数值仿真,并研究了重心位置移动和气动特性变化对飞机变形过程动态特性的影响规律。结果表明,折叠过程中气动特性的变化是影响飞机动态特性的主要因素,机翼折叠后飞机的速度和迎角增加,且飞行高度下降较大。

Longitudinal Multibody Dynamic Characteristics of Z-Wing Morphing Aircraft

The longitudinal multibody dynamic modeling and simulation of a Z-wing morphing aircraft in the wing morphing process is studied. When the wing is morphing, the wing area, moments of inertia, locations of aerodynamic center and center of gravity alter considerably, and these will change the dynamic characteristics of the aircraft. The six degree of freedom nonlinear dynamic functions of the morphing aircraft in the morphing process are derived. In addition, the decoupled longitudinal dynamic function is presented by simplification. The result of numeric simulation of aerodynamics in the wing folding process shows that the aerodynamics at various folding velocities is approximately the same. On condition that the wing fold angular velocity is small and the unsteady aerodynamic effect can be ignored, the longitudinal responses of the morphing aircraft in different wing fold angular velocities are numerically simulated by quasi-steady aerodynamic supposition. And the rules of how the dynamic characteristics are affected by the shift of center gravity position and variation of aerodynamics are investigated. The results show that the key factor which influences the morphing aircraft dynamic response in wing folding is the variation of aerodynamics. When the wing fold is completed, the flight velocity and angle of attack of the morphing aircraft will become larger, and its flight altitude will become considerably lower.