Effect of Ionic Wind Induced by DC Electric Field on Biogas/Air Turbulent Premixed Flame Structure

Abstract

ABSTRACT Effect of DC electric field on lean premixed biogas turbulent flame structure at low and medium turbulence intensity was studied experimentally using OH-PLIF. OH signal distribution, turbulent burning velocity and flame structure geometric parameters were derived. Results show that downward electric field could broaden the downstream burned gas and push the flame tip down. The flame base is closer to the burner rim in downward electric field for the modification of thermal diffusion and flow modification caused by ionic wind. The effect on flame tip height reduction is more obvious for biogas flame with a higher CO2 ratio. According to the flame structure analysis, the turbulent burning velocity of biogas is increased slightly due to the modification of flow field by ionic wind generated by downward electric field, and the increment decreases with the increase of turbulence intensity. In addition, there’s a decrease in mean flame surface density and an increase in centerline flame brush thickness. The flame surface curvature PDF distribution is nearly not affected by the application of DC electric field. For turbulent flames, the effect of electric field is non-uniform and inconstant, which induces extra flow perturbation. This perturbation is different from turbulence, and the combined effects lead to the variation of flame structure.