Effects of dimethyl ether and ethanol additions on soot transition in ethylene counterflow diffusion flames

This paper investigates the effect of blending dimethyl ether (DME) and ethanol on the soot transition periods in ethylene counterflow diffusion flames by using a novel optical diagnostic method. The soot critical transition point in different conditions is identified experimentally and numerically. Two kinds of flames are carried out to gain the soot critical transition point in counterflow diffusion flames by changing oxygen fraction (Xo) and changing volume flow rates of fuel and oxidizer (Qv). The red-green-blue (RGB) ratio method is used to precisely identify the soot critical transition point, and chemical kinetic simulations are performed to analyze the detailed reaction paths. The results show that compared to the ethylene flame, the soot critical transition point occurs at a higher Xo and a lower Qv when DME or ethanol is blended. The addition of DME and ethanol can inhibit soot formation, due to the degree of soot formation reaction being lower than the degree of the oxidation reaction in the blending flames.