Extinction Characteristics of Catalyst-Assisted Combustion in a Stagnation-Point Flow Reactor

As a fundamental study to understand physical and chemical characteristics in micro-combustors, numerical simulations of a stagnation-point flow combustor with a catalytic surface are performed. One-dimensional similarity formulation is derived with full consideration of detailed surface and gasphase chemical kinetic models. Parametric studies are conducted to investigate the effects of strain rate, equivalence ratio, heat loss on the combustion and extinction modes. The steady results showed that catalysis can largely extend the extinction limit, while suppressing the gas phase reaction at lower strain rates. It was also found that the extension of the catalytic reaction quenching limit is sensitive to the mixture composition, suggesting the dominance of chemical aspects in catalytic combustion. The temperature versus strain rate response curves exhibit multiple branches of stable solutions, implying a possibility of hysteresis behavior in a coupled homogeneous-heterogeneous reactor. Extensive parametric studies in terms of the mixture equivalence ratio and the conductive heat loss parameter have revealed three distinct steady response regimes. The results are expected to provide insight into improving the overall combustion stability and efficiency of micro-combustors.