Assessment and development of a novel reduced mechanism for methane combustion in computational fluid dynamics modeling

Abstract

The main objective of this work is to obtain the reduced reaction mechanism, which is consistent with a benchmark case in modeling a 0-D ignition delay, 1-D laminar flame speed, and 2-D simulated flame result and spent less processing time. In achieving this, the ten reduced reaction mechanisms developed for methane combustion were assessed, whereas the GRI-Mech 3.0 is considered a Benchmark. The result showed that only a reaction mechanism named SK30 was satisfactory. Still, the processing time in simulating the simple 2-D of a premixed model at the microscale was overly substantial. Subsequently, SK30 was further lessened using the two reduction steps. Firstly, the automatic algorithm based on a direct relation graph with the error propagation aided sensitivity analysis using ignition delays as a criterion in automatic reduction was applied. By doing this, the accuracy of ignition delays was maintained, and the flame speed was distorted. Accordingly, sensitivity analysis was employed to obtain the influential reaction in the benchmarking mechanism in the second step. The significant species and reactions on flame speed but less in ignition delay, which was missing in the current development, were considered to retrieve back manually as few as possible. Finally, the novel mechanism consisting of 25 species 132 reactions was proposed for methane-air combustion. In validation, the 1-D flame speed and the 2-D premixed flame model were agreement with the benchmark model. In addition, the processing time of this reduced mechanism was 50% faster than the SK30.