Strain Rate and Pressure Effects on Multi-branched Counterflow Flames
Abstract
This study presents methane-air counterflow simulations, in computationally efficient similar form, allowing combustible mixtures to flow from one or both directions in order to learn more about multi-branched propagating flame structures (e.g., a triple flame). These structures with both premixed and non-premixed flames are commonly seen in more practical combustion analyses. A range of realistic mass mixture fractions and asymmetric chemical rate laws are examined while avoiding the commonly forced unreal symmetric behavior with one-step second-order kinetics. Moreover, a survey of critical parameters is performed varying pressure and normal strain rate to define the flame structure and detect different characters. Three flames can co-exist if the strain rate is low enough and the pressure is high enough. However, at higher strain rate and/or lower pressure, only one or two flames might be obtained. Negative regions of heat release rate are observed and linked to potential endothermic reactions. With a rich premixed mixture at low strain rates and pressures, high exothermic reactions producing CO and HO, and consuming CO and H causes a heat-release-rate peak. Unexpected character of the lean and rich premixed flames is observed, leading to the conclusion that these flames are diffusion-controlled.
Keywords
Cite
@article{arxiv.2005.14516,
title = {Strain Rate and Pressure Effects on Multi-branched Counterflow Flames},
author = {Claudia-F. López-Cámara and Albert Jordà Juanós and William A. Sirignano},
journal= {arXiv preprint arXiv:2005.14516},
year = {2020}
}