湍流流动对MILD燃烧着火过程作用机理的非线性大涡模拟和实验研究

Comparing with traditional combustion technology, MILD combustion offers advantages of high efficiency, low noise and low emissions. Owning to the special conditions of MILD combustion, the physical mechanism is more complex than traditional combustions, and it makes high accuracy simulation of MILD combustion is challenging. In this project, we perform experimental measurements to provide modeling basis, and propose a large-eddy simulation (LES) framework to compute MILD combustion under turbulent conditions. The usage of advanced nonlinear subgrid-scale models enables us to more accurately simulate turbulent shear flows and others. To better understand the interactions of turbulence and combustion, the development of MILD flame, we further investigate its ignition process. The main research contents include: 1) experimental measurements of combustion cases to provide modeling basis; 2) study on the chemical mechanism for MILD combustion; 3) development of the nonlinear LES framework towards modeling the MILD flame ignition process; 4) study on the ignition process, the formation mechanism of initial auto-ignition, the interaction between turbulence and combustion, and flame propagation. The high fidelity simulation framework is constructed based on advanced sub-grid scale models and combustion models. Specific analysis of turbulence, mixing and combustion would reveal the physical mechanism of MILD combustion, and provide a scientific basis for understanding the combustion characteristics and controlling MILD flame, in order to promote the further development and application of MILD combustion technology.

相比传统燃烧方式，MILD燃烧在燃烧效率，噪音和排放等各方面都有明显优势，但MILD燃烧特殊的形成条件，使得对其进行高精度的仿真也相对困难。本项目通过实验测量，为湍流燃烧建模提供依据，构建求解湍流MILD火焰的大涡模拟（LES）方法，所采用的先进的非线性模型方法比传统方法更能准确计算湍流剪切等问题，并进一步对MILD燃烧着火过程进行仿真，获取其物化特性和时空变化规律。主要研究内容有：1）开展实验测量，提供建模依据；2）MILD燃烧化学反应动力学的机理研究；3）构建计算湍流MILD火焰着火过程的非线性LES方法；4）探究初始自燃着火的形成机理，湍流与自燃和火焰传播之间的相互作用。本研究从亚网格和燃烧建模入手，构建一个高精度的 LES 方法，并具体分析湍流场中的流动、混合和燃烧的动态过程，能为揭示MILD燃烧形成机制、燃烧特性以及控制方法提供科学依据，以促进MILD燃烧技术的进一步发展。

相比传统燃烧方式，MILD燃烧在燃烧效率，噪音和排放等各方面都有明显优势，但MILD燃烧特殊的形成条件，使得对其进行高精度的仿真也相对困难。本项目通过实验测量，为湍流燃烧建模提供依据，构建求解湍流MILD火焰的大涡模拟（LES）方法，所采用的先进的非线性模型方法比传统方法更能准确计算湍流剪切等问题，并进一步对MILD燃烧着火过程进行仿真，获取其物化特性和时空变化规律。主要研究内容有：1）开展文献实验数据的收集和实验测量，提供建模依据；2）耦合适用于求解MILD火焰的燃烧模型和化学反应动力学机理，构建计算湍流燃烧和MILD火焰的非线性LES方法；3）探究MILD着火的形成机理，湍流与燃烧之间的相互作用。本研究从亚网格和燃烧建模入手，构建一个高精度的 LES 方法，并具体分析湍流场中的流动、混合和燃烧的动态过程，能为揭示MILD燃烧形成机制、燃烧特性以及控制方法提供科学依据，以促进MILD燃烧技术的进一步发展。