Ignition and Flame Propagation in Methane-Air Multi-Stratified Vortical Flow Field

Abstract

The objective of this study is to analyze the flame propagation under the interaction between fluid mechanics and chemical kinetics in a counter shear layer. First, a large-scale Kelvin-Helmholtz instability is triggered by initially-imposed linear perturbations to form a multi-stratified vortical layer. Second, mixed reactants in such a stratified vortex are ignited by local energy addition where flame propagation under the effect of instability is observed. Three different ignition locations are selected to examine combustion efficiency. The ignition in a vortex core shows a 1.7 times C0₂ productivity in comparison with the ignition in a braid region: The most advantageous ignition position for C0₂ productivity is the vortex core region where the mixture strength is high and the flammable mixture spreads rapidly. Once formed, a wrinkled diffusion flame propagates through the multi-stratified mixture, destroying the initially existing vortical structure. In addition, a Lewis number analysis in the vicinity of flame region shows flame instability and local extinction.

Keywords:

• Ignition
• methane
• flame propagation
• multi-stratified layer
• vortical flow field
• flame stability