Influence of chordwise bending stiffness on aeroelastic characteristics of flexible high-aspect-ratio wing
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摘要: 高空长航时飞机普遍采用小后掠角大展弦比机翼,飞行时机翼具有较大变形.几何非线性加剧机翼结构水平弯曲与扭转的刚度耦合,水平弯曲模态在颤振分析中的作用已不可忽略,对机翼气动弹性特性影响显著.将结构在给定来流攻角的静平衡位置附近线化,以求解结构的固有振动特性,并应用考虑翼面变形的片条理论计算非定常气动力,用 p-k 法计算颤振速度.以金属梁式机翼为对象的颤振计算结果表明,水平一弯模态参与耦合的机翼颤振速度低于线性颤振速度.增大水平弯曲刚度有助于这类颤振速度的提高,而扭转频率的影响也要加以考虑.Abstract: High-aspect-ratio wing with low sweepback has been widely adopted by high-altitude long-endurance (HALE) aircrafts, and the wing boasts large deformation due to flight load. The coupling of stiffness between chordewise bending and torsion is intensified by the geometric nonlinearity, and chordwise bending mode plays key role in affecting the aeroelastic characteristics of the wing. Linearization of the structure was performed near its static equilibrium state under specific attack angle. Natural frequencies and mode shapes of the deformed wing were obtained, while the unsteady aerodynamics of the curved wing was calculated through strip theory. The flutter speed was determined by p-k method. Through the calculation of a metal beam wing, it can be concluded that there is a lower flutter speed with chordwise bending mode involved in coupling than without. Increase of chordwise bending stiffness is helpful for raising this flutter speed, and the effect of the torsional frequency should also be considered.
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