高精度数值格式在热化学非平衡流模拟中的应用研究

High-order accurate schemes have special advantages in the simulaiton of fine flow structures for their maintainability of high accuracy and high resoluiton with relatively lower requirement for the computational resource. In the complex hypersonic flow with shock wave—boudary-layer and shock—shock interactions, high-order schemes have been used, but mostly in the flows without chemical reactions where the carloricallly perfect gas assumption is adopted. This project aims at the application and investigation of high-ordr schemes in the simulaiotn of high-temperature nonequilibrium flow, which can not only extend the application range of high-order scheme, but also deepen the study of high-temperature nonequilirium flow and improve the accuracy of prediction for the aerodynamic perfromance of hypersonic vehicles. Firstly, the synthetic application stategy of higher-order and second-order schemes will be investigated on account of the complexities introduced by both the higher-order schemes and the high-temperature chemical reactions. Secondly, the high-order accurate method to deal with the boundary conditions at the wall with catalyticy and ablaiotn is studied based on the mechanisms of gas-interface interaction. Thirdly, the code using high-order schemes will be developed and then verificated and validated through experiments in high-enthalpy tunnels. Finally, the devloped code with high-order accuracy will be used in the numerical simulation of high-temperature nonequilibrium flow with shock wave—boudary-layer and shock-shock interactions, the fine structures and the intrinsic flow mechanisms will be investigated thoroughly.

高精度格式因其在较低的计算资源消耗下仍能保持足够精度而在精细流动结构的模拟中具有独特优势。在激波/激波、激波/边界层相互作用等复杂高超声速流动中，高精度格式也已得到应用，但主要限于量热完全气体流动。本项目进行高精度格式在热化学非平衡流动中的应用研究，这既是对高精度格式应用领域的拓展，也是非平衡流研究内容的深入和更加精确预测高超声速飞行器气动特性的需要。包括：(1) 针对高温化学反应和高精度格式应用的双重复杂性，研究综合高阶和二阶格式以实现高精度和高效非平衡流模拟的策略。（2）结合气-壁相互作用机理分析，研究存在壁面催化和烧蚀时高精度的壁面边界条件处理方法。(3)对典型算例开展高焓风洞的对比实验研究，测试本项目发展的高精度非平衡流数值计算程序的有效性。（4)应用高精度计算程序开展存在激波/激波、激波/边界层相互作用的高温非平衡流动数值模拟，着重对复杂流场精细结构的辨识和机理研究。

基于高精度格式在精细流动结构捕捉方面的优势，非平衡流研究内容深入和更加精确预测高超声速飞行器气动特性的需要，进行高精度格式在热化学非平衡流动中的应用研究。. 在热化学非平衡流计算程序中引入5阶WCNS格式，针对高阶格式在化学反应流应用中的鲁棒性问题采取措施，将高阶格式计算程序成功应用于热化学非平衡二维圆柱绕流、轴对称球锥绕流、二维压缩拐角流动数值模拟；提高了对复杂流场精细结构的辨识能力，综合应用高阶和2阶格式，兼顾了计算的精度、稳定性和效率。实现了高阶精度程序的并行化，可用于典型高超声速飞行器三维高温非平衡流场计算。. 完成了存在烧蚀的高精度壁面边界条件处理方法，关于烧蚀对激波边界层相互作用流动研究应的分析可为存在烧蚀再入飞行器气动热与气物理特性的预测提供参考依据。. 完成了高焓风洞喷管流场及风洞中二维和三维压缩拐角、双楔流动的数值重建与机理分析，关于风洞中激波/激波边界层相互作用和激波/激波相互作用流动特性的研究及风洞自由流非平衡对流动特性影响的分析，为高焓风洞实验研究的开展和研究结果的有效使用做出了积极贡献。. 完成了采用态-态模型的O2/O系统热化学非平衡与辐射过程模拟程序编制，进行的典型非平衡辐射过程数值模拟和对各类跃迁或化学反应过程以及辐射跃迁过程对系统化学组成和分子振动能级分布变化的贡献的分析，为更好理解O2/O和高温空气热化学反应机理提供新的思路，也为今后采用态-态模型研究高温空气的非平衡过程并进一步与流动耦合奠定基础。