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ISSN Online: 2688-7231

ISBN Online: 978-1-56700-524-0

Proceedings of the 26thNational and 4th International ISHMT-ASTFE Heat and Mass Transfer Conference December 17-20, 2021, IIT Madras, Chennai-600036, Tamil Nadu, India
December, 17-20, 2021, IIT Madras, Chennai, India

Numerical Investigation on the Lewis Number Effects on the Turbulent Premixed Swirl Stabilized Propane-Air Flames

Get access (open in a dialog) DOI: 10.1615/IHMTC-2021.2580
pages 1713-1719

Abstract

Interaction of Coherent Precessing Vortex Core(PVC) as well as the preferential diffusional effects on the turbulent premixed swirling propane-air flames at different Lewis numbers (Le) with high Karlovitz (Ka) and low Damkohler Number (Da) values were studied numerically. For this, the swirl burner reported in the literature having swirl number S=1.05 was adapted, recreated and simulated using ANSYS Fluent. Computational analysis was initiated with propaneair mixture having equivalence ratio, ∅=2 (Le=0.879) at 573K and 1 bar, using RANS and DDES. Present simulation results were successfully validated with the experimental data from literature. DDES showed good agreement with experiments. With the same model, the combustible mixtures having ∅=1(Leeff =1.36) & ∅=0.6(Le=1.735), keeping the Reynolds number nearly same were simulated. Time-averaged axial velocity and temperature indicated that the flames stabilized in the Inner shear layer( ISL) where strong vortices dominates. Flame, at stoichiometric condition, was anchored most upstream due to its relatively shorter reaction time and was the longest among the three due to higher fuel mole fraction. Borghi diagram reveals that flame region in fuel rich condition(Le<1) was most stretched, thickest, reaction controlled and Kolmogorov eddies controls the flame zone too. Stoichiometric condition is least corrugated though its RMS velocity magnitude & integral length scale values were comparable to rich and lean conditions respectively. Time series analysis indicates that in the fuel lean condition, vortices shed early and with greater frequency from the ISL in the combustion chamber as compared to other two conditions forming relatively stronger PVC that even stabilizes the flame with Le>>1 having Ka is nearly 100 and Da<1.