Effect of DC Electric Field on Turbulent Flame Structure and Turbulent Burning Velocity

Effect of electric field on turbulent premixed flame structure and turbulent burning velocity is investigated through OH-PLIF technique. The ring-plate electrode configuration is used, which the ring electrode is high potential. Flame front structure and turbulent burning velocity are derived to estimate the effect of electric field on turbulent flame. Results show that electric field has similar effects compared with turbulence to some extent in this experiment, which could increase flame volume, turbulent burning velocity and decrease the flame surface density. But there are still substantial distinctions in detail. The perturbation induced by turbulence is the vortex, while that induced by electric field is the directional flow, and it can be verified through the PDF distribution of flame curvature with/without electric field. Effect of electric field is a local effect because it is dependent on the distribution of charged species. The research indicates electric field-assisted combustion is mitigated by the turbulence to some extent, and it may hinder the utilization of electric field at practical application for combustion enhancement, but other aspects need further researches. Two reasons are proposed to explain the mitigation of turbulence. Firstly, the response of turbulent burning velocity to the same perturbation decreases with turbulence intensity. Secondly, the wrinkled structure of turbulent flame mitigates the effect of electric field.