The effects of large flame deformation on the premixed flame combustion structure were studied by means of a 2-D numerical experiment with detailed chemical kinetics and accurate transport properties, in which a high-speed unburnt gas volume was injected into a stationary hydrogen-air premixed flame of equivalence ratio 4.5. It was found that an extraordinarily high fuel consumption rate appears in the course of the gas volume penetration into the premixed flame. Full use of the numerical data was made to understand the cause of this phenomenon. It was found that enthalpy accumulation that takes place when the flame merges plays a key role: an increase in high-temperature unburnt O 2 produced by the accumulated enthalpy accelerates the productions of OH and O, leading to the acceleration of H 2 consuming reactions. A similarly extraordinarily high fuel consumption rate in a turbulent rich premixed flame has previously been observed in the 3-D simulation of a hydrogen jet lifted flame, and therefore the mechanism found in this study may be one of the key mechanisms to understand in the behavior of turbulent premixed flames. (c) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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