Direct numerical simulation of nonpremixed syngas burning with detailed chemistry

Abstract

Hydrogen/carbon monoxide non-premixed syngas impinging jet flames were studied using three-dimensional direct numerical simulation (DNS) and flamelet generated manifolds (FGM) based on detailed chemical kinetics. The computational domain employed has a size of 4 jet diameters in the streamwise direction and 12 jet diameters in the cross-streamwise direction. The results presented in this study were performed using a uniform Cartesian grid with 200x600x600 points. The Reynolds number used was Re=2000, based on the inlet reference quantities. The spatial discretisation was carried out using a sixth-order accurate compact finite difference scheme and the discretised equations were temporally advanced using a third-order accurate fully explicit compact-storage Runge-Kutta scheme. Results show that the ratio of hydrogen and carbon monoxide in the syngas mixture significantly changes the flame characteristics including near-wall flame structure. The high diffusivity of hydrogen-rich syngas flame forms weaker vortices, results in a thicker flame. In contrast, carbon monoxide-rich syngas flame forms strong wrinkles, results in a thinner flame. Moreover, the DNS results suggest that the preferential diffusion influences the local flame structure for the simulated low Reynolds number hydrogen flame.

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ORCID for K.K.J. Ranga Dinesh: orcid.org/0000-0001-9176-6834

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