A Non-Linear Model for the Longitudinal Dynamics of a Hypersonic Air-breathing Vehicle
A Non-Linear Model for the Longitudinal Dynamics of a Hypersonic Air-breathing Vehicle
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DOI：
10.2514/6.2005-6255
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发表时间：
2005-08
期刊：
影响因子：
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通讯作者：
M. Bolender;D. Doman
中科院分区：
文献类型：
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作者：
M. Bolender;D. Doman
摘要建立了吸气式高超声速飞行器纵向动力学的非线性物理模型。该模型由第一性原理推导而来，捕捉了推进系统、空气动力学和结构动力学之间复杂的相互作用。与传统飞机不同，高超音速飞行器要求推进系统高度集成到机身中。此外，高超音速飞机往往具有非常轻、灵活的结构，具有低固有频率。因此，机身的第一弯曲模式很重要，因为它的偏转会影响进入发动机的气流量，从而影响推进系统的性能。利用拉格朗日方程推导了柔性飞行器的运动方程。飞行器俯仰加速度和法向加速度与结构动力学之间的运动捕捉惯性耦合效应。线性化的飞机动力学被证明是不稳定的，在大多数情况下，表现出非最小相位行为。线性化模型还表明，存在固有频率为机身弯曲模态频率两倍以上的气动弹性模态。此外，短周期模态与机身弯曲模态耦合非常强。
Abstract : A non-linear, physics-based model of the longitudinal dynamics for an air-breathing hypersonic vehicle is developed. The model is derived from first principles and captures the complex interactions between the propulsion system, aerodynamics, and structural dynamics. Unlike conventional aircraft, hypersonic vehicles require that the propulsion system be highly integrated into the airframe. Furthermore, hypersonic aircraft tend to have very lightweight, flexible structures that have low natural frequencies. Therefore, the first bending mode of the fuselage is important as its deflection affects the amount of airflow entering the engine, thus influencing the performance of the propulsion system. The equations of motion for the flexible aircraft are derived using Lagrange's Equations. The equations-of-motion capture inertial coupling effects between the pitch and normal accelerations of the aircraft and the structural dynamics. The linearized aircraft dynamics are shown to be unstable, and in most cases, exhibit non-minimum, phase behavior. The linearized model also indicates that there is an aeroelastic mode that has a natural frequency more than twice the frequency of the fuselage bending mode. Furthermore, the short-period mode is very strongly coupled with the bending mode of the fuselage.