激波作用碳氢可燃气泡中高效燃烧机理研究

The high efficient combustion of hydrocarbon fuel is one of a critical engineering problem that is one of the main obstacles in the development of scramjet. In order to solve this problem, it desperately needs an in-depth understanding of the coupled process between flow and combustion in the supersonic environment. In this project, we focus on a fundamental flow problem, the unsteady evolution of vortex structures induced by the shock/reactive bubble interaction, which is abstracted from the complex flow processes in scramjet. Based on the high efficient parallel technology and the Large Eddy Simulation (LES), both the evolutionary characteristics and influence factors on vortex structures induced by the shock bubble interaction are presented. With the help of the Lagrangian Coherent Structures (LCS) which is developed for exactly capturing vortex boundary in supersonic compressible flow problems, the fuel mixing model dominated by unsteady vortex structures is established. From the changing flow angle and combustion angle, the numerical results offer the key factors on influencing the coupling relations between the flow structures and combustion, the mechanisms of which are established as well. The research findings will not only provide an advanced theoretical foundation of flow propulsion for the design of scramjet, but also help to reveal some essential features of supersonic reactive flows.

碳氢燃料在超声速环境下高效燃烧一直是超燃冲压发动机发展中面临的核心工程问题之一，解决此问题需要深入认知超声速环境下流动燃烧耦合过程。本项目聚焦在超燃冲压发动机中抽象出的基础模型问题：激波作用可燃气泡诱导的非定常涡结构演化过程。通过高效并行技术及高精度大涡模拟技术，数值研究激波作用气泡诱导涡系结构演化特征和形态的影响规律；发展针对超声速问题的非定常涡边界捕获LCS方法，在精确捕获到非定常涡边界的基础上提出了由非定常涡结构主导的燃料混合模型。随后分别从流动和化学的角度对比分析给出了影响流动和燃烧耦合作用的关键因素，并且建立超声速环境下涡致混合流动结构与燃料燃烧的耦合作用机理。本项目研究成果不仅能为超燃冲压发动机提供先进的流动推进理论基础，同时也可以揭示超燃环境下超声速流动的一些本质特征。

超声速环境下的氢燃料高效燃烧一直是超燃冲压发动机发展中面临的核心工程问题之一，迫切需要对燃烧流动耦合物理机制深入开展研究。本项目聚焦在超燃冲压发动机中激波与射流相互作用抽象出的基础模型问题：激波作用可燃气泡诱导的非定常涡结构演化过程。数值方面开展了一系列激波作用气泡诱导涡系结构演化特征和形态的影响规律的研究；提出了针对超声速问题的非定常涡边界捕获LCS方法，并提出了三阶段的激波作用混合演化规律，发展高斯分布的混合模型。随后对激波作用可燃气泡相互作用，发现燃烧效率无法进一步通过激波增强，基于涡结构演化特征提出了燃烧效率改进方法，实现燃烧效率提高50%以上。本项目研究成果不仅能为超燃冲压发动机提供先进的燃烧动力理论基础，同时也可以揭示超燃环境下超声速湍流燃烧的一些本质特征。