垂直/短距起降飞机非线性动力学建模与仿真

垂直/短距起降(V/STOL)飞机具有广泛而高效的军事应用前景.为研究V/STOL飞机复杂的飞行控制问题,需要建立能够准确反映其动态特性且可用于飞行仿真的动力学模型.综合考虑V/STOL飞机的多进气道气流量变化、大迎角非线性和迟滞非定常特性、地面效应和喷气诱导效应等因素的影响,利用线性叠加原理并结合机理建模与经验公式,建立了全面的推进/气动力与力矩模型;在此基础上,基于刚体动力学和运动学原理,推导得到了V/STOL飞机的全状态六自由度非线性数学模型;最后,仿真分析了V/STOL飞机的地面效应和喷气诱导效应引起的动力学变化及其三角翼非定常动力学特性.结果表明:地面效应对V/STOL飞机动力学的影响可以忽略,而近地飞行时的喷气诱导效应会导致较大的升力损失,离地越近损失越大;V/STOL飞机的非定常动力学源于飞机迎角变化所引起的气动力滞环效应,且迎角越大、空速越小,滞环效应越显著,非定常动力学特性越强.所建模型物理意义明确、计算方便,能够较为准确地反映V/STOL飞机的动力学特性,可为其不同飞行模式下的模型简化应用和飞控系统设计提供帮助.

Nonlinear aerodynamic modeling and simulation of vertical and/or short take-off and landing aircraft

There are wide and efficient military application prospects for the vertical and/or short take-off and landing (V/STOL) aircraft. A dynamic model of V/STOL aircraft accurately reflecting the dynamic characteristics in flight simulation should be built for research on its complex flight control. By employing the principle of linear superposition and combining the mechanism modeling and empirical formula, a complete propulsion/aerodynamic force and torque model was built considering the impacts of the changing rate of gas mass flow, nonlinear and unsteady dynamic characteristics at high angle of attack, unpowered ground effect, and jet-induced effect. By applying this model, the 6-DOF nonlinear mathematic model was deducted according to the principle of rigid body dynamics and kinematics. Finally, simulation analysis provided the dynamic changes of V/STOL aircraft caused by ground effect, the jet-induced effect and the unsteady dynamic characteristics of the delta wing. Results indicate that the effect of ground effect on the dynamics of V/STOL aircraft can be ignored, while the jet-induced effect in near ground flight leads to greater lift loss that increases with the decreasing flight altitude. The unsteady dynamics of V/STOL aircraft which is derived from the hysteresis effect caused by the change of angle of attack is significant at high angle of attack and small airspeed. This model has the characteristics of clear physical meaning and simple calculation, can reflect the dynamic characteristics more accurately, and can provide help for model simplification and flight control system (FCS) design in different flight modes for the V/STOL aircraft.