Electrical characteristics of laminar propane flame during head-on quenching

Abstract

The electrical characteristics of laminar propane flame during head-on quenching were investigated experimentally and computationally. A variable small electric field was applied between the burner and the quenching plate, which recorded flame current as a function of the height of the quenching plate, for both polarities, different premixed-air volume, and quenching plate materials. More detailed information of flame, such as the distribution of OH radical and main charged species (H3O+ and e−) were obtained by using numerical simulation. The results showed that during the head-on quenching, the resistance of the propane flame is on the order of 108 Ω, the flame current increases with the increase of the premixed-air volume, and the effect of the quenching plate materials on the flame current is negligible. In addition, it is found that the direction of the electric field has a significant influence on the flame current, indicating the “rectifier” characteristics of the flame. Moreover, it is interestingly found that the trend of flame current for burner− (burner is negative) is more consistent with the trend of the maximum OH mole concentration than for burner+ (burner is positive), which indicates that the trend of flame current for burner− can more accurately reflect the combustion state during head-on quenching. And it would be a better choice to use burner as the negative electrode when diagnosing the combustion state with an applied electric field.