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高空长航时(HALE)飞机结构细长、具有柔性,在常规飞行条件下可发生结构大变形、气动失速以及结构低频振动与刚体运动耦合,这些现象显著影响其静、动态特性。基于几何精确完全本征运动梁模型、ONERA动失速气动力模型和六自由度刚体运动模型,建立了考虑几何非线性、动失速和材料各向异性等因素的大展弦比柔性飞机非线性气动弹性与飞行动力学耦合模型。使用常规布局和飞翼布局两种柔性飞机算例模型,对大展弦比柔性飞机非线性气动弹性与飞行动力学耦合配平、动稳定性和时域响应特性开展了研究。研究结果表明:当机翼变形较小时,柔性飞机配平迎角小于刚性飞机配平迎角,整个翼展范围内均可能发生失速,全机升力损失显著,可导致飞行高度迅速降低;当机翼变形较大时,柔性飞机配平迎角大于刚性飞机配平迎角,失速发生于翼尖且范围有限;机翼变形增大可导致全机运动趋于不稳定,气动弹性剪裁有助于改善柔性飞机动稳定性。
The structure of HALE aircraft is slender and flexible. Large deformation, aerodynamic stall and structural low frequency vibration can be coupled with rigid body under normal flight conditions. These phenomena significantly affect the static and dynamic characteristics. Based on the geometrically exact and completely moving beam model, the ONERA dynamic-aerodynamic model and the six-degree-of-freedom rigid body motion model, the nonlinear aerodynamic characteristics of a large aspect-ratio flexible aircraft considering geometrical nonlinearity, dynamic stalling and material anisotropy were established. Elasticity and Flight Dynamics Coupling Model. Two typical examples of flexible aircraft models are used to study the nonlinear aerodynamic and aerodynamic coupling, dynamic stability and time-domain response of large aspect ratio flexible aircraft. The results show that when the deformation of the wing is small, the angle of attack of the flexible aircraft is smaller than that of the rigid aircraft, and the stalling may occur in the whole span of the whole span. The loss of lift of the whole aircraft is significant and the flying height can be rapidly reduced. Larger, the angle of attack of the flexible aircraft is larger than that of the rigid aircraft. The stall occurs at the tip of the wing and has a limited range. The increase of the wing deformation can lead to the instability of the whole aircraft. Aeroelasticity cutting can help to improve the flexibility of the aircraft stability.