超声速燃烧数值模拟中复杂化学反应的建模方法

Modeling methodology for complex chemical mechanism involved in supersonic combustion simulation

高保真度的数值模拟有助于研究超声速条件下点火、熄火、火焰传播以及稳焰等关键物理-化学过程,推动对冲压发动机中复杂燃烧现象的准确理解与可靠预测。然而,实际发动机中碳氢燃料燃烧导致的广泛时空尺度对湍流燃烧的建模带来了极大的挑战。为此,必须首先解决超声速燃烧数值模拟中复杂化学反应的高保真建模问题。本文对超声速燃烧模拟中湍流-化学反应相互作用模型、机理简化以及求解加速方法的研究现状进行了总结。以典型燃料燃烧建模为主线,介绍了复杂化学反应的高保真建模方法以及不同化学反应机理在超燃模拟中的适用性及其影响。以反应机理三层次保真度评估体系为基础,进一步明确了简化机理在超燃数值模拟中的优势与不足,阐明了动态自适应化学方法在研究超声速条件下细致燃烧过程的必要性和可行性。

High-fidelity numerical simulation is considered as an indispensable approach to reveal key physical-chemical process such as ignition,extinction,flame propagation,and stabilization in supersonic flows,and promotes accurate understanding and reliable prediction of complex combustion phenomenon in ramjet engines.However,the extensive spatiotemporal scales caused by the combustion of hydrocarbon fuels in actual engines pose great challenges to turbulent combustion modeling.To overcome these challenges,high-fidelity modeling of complex chemistries in numerical simulation of supersonic combustion should be carefully handled.This paper gives a summary of the main research progresses in turbulence-combustion interaction model,mechanism reduction,and solution acceleration methods in supersonic combustion simulation.Taking typical fuels as prototypes,the high-fidelity modeling of complex chemistries,as well as applicability and influences of different chemical mechanisms in supersonic combustion are introduced.Based on the three-level fidelity evaluation methodology of chemical mechanism,the advantages and disadvantages of reduced mechanism are further clarified,and the necessity and feasibility of using dynamic adaptive chemistry method in the investigation of detailed combustion processes in supersonic flows are also elaborated.