高超声速典型弹道下的壁板热气动弹性动力学分析

Dynamics analysis of panel aerothermoelasticity in typical hypersonic trajectories

对高超声速流中带有热防护系统(TPS)的二维壁板进行了热气动弹性的双向耦合建模与分析,采用三阶活塞理论计算气动力,通过参考焓法获得气动热流,在有限差分法的基础上进行结构热传导计算,拟合了结构材料特性随温度退化的曲线,最后将气动热模块、气动弹性模块进行双向耦合以考虑气动热与结构形变之间的相互反馈,并在2种典型弹道状态下进行热气动弹性响应分析。结果表明,在X-34A的设计弹道下,双向耦合分析会引起更加剧烈的热应力与热弯矩的变化与较长的瞬态混沌过程。在FALCON弹道下,双向耦合得到的结果加热更为剧烈,而温度下降的过程也更快。对比2种弹道发现,长时间的高超声速飞行更容易引发颤振,而机动性较强的弹道面临的主要问题则是屈曲,需要考虑材料的应力及强度特性。同时说明了双向耦合策略对于现代飞行器在弹道状态下工作的热气弹响应分析的必要性。

This study builds a two-way coupling model of aerothermoelasticity for two-dimensional panels with TPS in hypersonic flow. The aerodynamic force is calculated by the third-order piston theory, the aerodynamic heat obtained by the Eckert’s reference enthalpy method, and the heat transfer carried out on the basis of the finite difference method, with the material properties of the structure fitted with temperature degradation. Finally, the aerothermal module and the aeroelastic module are two-way coupled considering the effect of panel deflection on aerodynamic heat flux, and the aerothermoelastic analysis is conducted in two typical trajectories. The results show that the two-way coupling analysis would cause more severe changes in thermal stress and thermal bending moment, leading to a longer transient chaos for the X-43 A trajectory. In the FALCON trajectory, with the two-way coupling, the aerodynamic heating is more intense with a faster temperature drop. Comparison of the two trajectories demonstrates that long-term hypersonic flights are more likely to cause flutter. However, the main problem faced by stronger maneuverability trajectories is buckling, and the strength characteristics of the material need to be considered. Furthermore, it illustrates the necessity of two-way coupling analysis to accurately obtain the aerothermoelastic response of modern aircraft under trajectory conditions.