高速飞行器结构/气动/推力耦合动力学建模方法

Dynamic modeling of a hypersonic vehicle with structure, aerodynamic and propulsion coupling

  • 摘要: 高速飞行器采用细长体布局和推进-机体一体化设计,并大量使用轻质材料、薄壁结构。这些因素造成推进系统与气动力、结构变形之间的相互影响,带来特殊的推力-气动弹性耦合问题。针对此类问题,本文基于飞行力学小扰动理论建立动力学方程,引入当地流活塞理论显式气动力模型、模态法结构变形模型和准一维超燃冲压发动机模型等兼顾分析精度和效率的子学科模型,提出了一种结构-气动-推力耦合的吸气式高速飞行器动力学建模方法。采用此方法针对类X-43典型高速飞行器二维模型进行动力学稳定性分析,包括推力及弹性耦合对飞行器动力学特性产生的影响和对关键耦合参数的变参分析。分析结果验证了建模方法的可行性,并证明了推力-气动弹性耦合对飞行器动力学特性的特殊影响,其中推力耦合会显著降低长周期稳定性,弹性耦合会略微增加短周期稳定性,而舵偏振动耦合则会显著降低短周期稳定性。

     

    Abstract: Hypersonic vehicle often uses a propulsion-airframe integrated design, and often has a slender body layout using thin-walled structure and lightweight materials. These factors cause serious coupling effects between propulsion system, aerodynamic force and structural deformation, then lead the ensuing special propulsion-aeroelastic coupling problems. Given these, integrated dynamic modeling and analysis methods were studied. Firstly, dynamic equations were established based on small-perturbation theory of flight dynamics. Then the sub-discipline models with both high accuracy and efficiency were employed, which were aerodynamic model based on local piston theory, structural deformation model based on modal method and quasi-one-dimensional scramjet model. Finally, a dynamic model of air-breathing hypersonic vehicle considering the coupling of propulsion system and structural deformation was established. The dynamic stability analysis of a X-43-liked two-dimensional model is carried out based on the dynamic model. The effects of propulsion and aeroelastic coupling on the dynamic characteristics of the aircraft model are analyzed, and variable parameter analysis of key coupling parameters are conducted. The results validated the feasibility of these dynamic modeling & analysis methods, and demonstrate the special influence of propulsion-aeroelastic coupling on the dynamic characteristics of the example aircraft model. The propulsion coupling can significantly reduce the Phugoid mode stability, the aeroelastic coupling can slightly increase the short period mode stability, and the elevator deflect vibration coupling can significantly reduce the short period mode stability.

     

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