Math. Model. Nat. Phenom.
Volume 13, Number 6, 2018
Mathematical modelling in combustion sciences
|Number of page(s)||16|
|Published online||27 September 2018|
Dynamics of lean premixed flames stabilized on a meso-scale bluff-body in an unconfined flow field
Clean Combustion Research Center, King Abdullah University of Science and Technology (KAUST),
23955-6900, Saudi Arabia
2 School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
* Corresponding author: firstname.lastname@example.org
Accepted: 18 July 2018
Two-dimensional direct numerical simulations were conducted to investigate the dynamics of lean premixed flames stabilized on a meso-scale bluff-body in hydrogen-air and syngas-air mixtures. To eliminate the flow confinement effect due to the narrow channel, a larger domain size at twenty times the bluff-body dimension was used in the new simulations. Flame/flow dynamics were examined as the mean inflow velocity is incrementally raised until blow-off occurs. As the mean inflow velocity is increased, several distinct modes in the flame shape and fluctuation patterns were observed. In contrast to our previous study with a narrow channel, the onset of local extinction was observed during the asymmetric vortex shedding mode. Consequently, the flame stabilization and blow-off behavior was found to be dictated by the combined effects of the hot product gas pocket entrained into the extinction zone and the ability to auto-ignite the mixture within the given residence time corresponding to the lateral flame fluctuations. A proper time scale analysis is attempted to characterize the flame blow-off mechanism, which turns out to be consistent with the classic theory of Zukoski and Marble.
Mathematics Subject Classification: 80A25 / 76F65 / 76D05 / 65L06 / 80A32 / 76B47 / 76N15
Key words: Direct numerical simulation / Flame dynamics / Bluff-body stabilization / Premixed flames / Blow-off
© EDP Sciences, 2018
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