NUMERICAL STUDY ON TURBULENCE EFFECTS IN POROUS BURNERS

Abstract

This paper presents numerical simulation of combustion of air/methane mixture in a cylindrical porous burner while the turbulence between the pores of porous medium has been considered via an explicit model. Results of both laminar and turbulence models are presented and compared for different equivalence ratios and several pore diameters. The turbulent kinetic energy increases along the burner due to the turbulence created by the solid matrix with a sudden jump at the flame front due to the thermal expansion. Also, because of the higher diffusion due to the turbulence, the reactants become more preheated, leading to an increase in the burning speed in comparison to the laminar results. Higher burning speed in turbulence cases decreases the flame temperature and shifts the maximum temperature location toward downstream of the burner. It is found that at higher equivalence ratios, the effects of turbulence become more significant. Taking into account the turbulence effects results in burning speeds which are in good agreement with the experimental data. Although the increase of pore diameter in the laminar model decreases the burning speed due to lower volumetric heat transfer between the phases, higher effective diffusion results in higher burning speed in the turbulence model.