考虑稀薄效应的再入飞行器前缘热化学反应与烧蚀模型研究

An investigation of thermochemical reaction and aerodynamic ablation model on leading edges of reentry vehicles considering rarefaction effect

  • 摘要: 高温气流与飞行器表面材料的多物理、化学作用导致飞行器表面形貌的显著变化,影响流动结构演化与飞行器气动力、热特性。准确预测再入过程的表面材料烧蚀过程对于飞行器热防护系统的设计至关重要。现有的气动烧蚀数值模拟研究主要针对固定壁面温度条件的流场变化,忽视了烧蚀过程中复杂化学反应与壁面材料性质差异导致的升温过程及烧蚀形貌的影响。本研究基于直接模拟蒙特卡洛(DSMC)方法,耦合壁面能量守恒方程,采用开源程序SPARTA对飞行器再入时的气动加热过程开展解耦分析。以柱体模型为例,综合激波后的气-气与气-固化学反应,对解耦后的壁面升温和模型烧蚀两个过程分别建立了相应的控制方程,并分析了在二维条件下的热化学反应与气动烧蚀机制。研究结果表明,本文开发的可计算烧蚀模型不仅能够提升激波后气体分子内能采样的准确性,也能够复现文献中已有的烧蚀形貌。该方法能够为深入理解变壁面温度下的复杂热化学非平衡现象提供理论依据与数据支撑。

     

    Abstract: High-temperature airflow interacts with the surface materials of aircraft through multiple physical and chemical processes, significantly altering the aircraft's surface morphology. This affects the evolution of flow structures as well as the aerodynamic and thermal characteristics of the surface. Accurate prediction of the ablation process during re-entry is crucial for designing thermal protection systems. However, existing studies on aerodynamic ablation primarily focus on flow fields under fixed wall temperature conditions, neglecting the impacts of complex chemical reactions and differences in wall material properties on heating and ablation morphology. This study employs the direct simulation Monte Carlo (DSMC) method, coupled with the wall energy conservation equation, and utilizes the open-source program SPARTA to analyze the aerodynamic heating process during high-speed flight. Taking a cylindrical model as an example, this study establishes separate control equations for wall heating and material ablation. By integrating gas-gas and gas-solid chemical reactions, the new ablation model is used to analyze aerodynamic ablation mechanisms of different wall materials. The results indicate that the proposed ablation model enhances the accuracy of internal energy sampling of particles post-shock and replicates existing erosion morphologies from literature. This method offers theoretical basis and data support for understanding complex thermochemical non-equilibrium phenomena under variable wall temperatures.

     

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