Experimental Investigation on Soot Formation in an Ethylene/Air Laminar Diffusion Flame Diluted with C0_2 at Pressures up to 8 atm

摘要

The effects of C0_2 addition to the fuel on the temperature field and soot formation in a co-flow laminar diffusion flame of ethylene/air over the pressure range of 1 to 8 atm were investigated experimentally. The flame was produced in a high pressure combustion chamber. A technique of diffuse-light two-dimensional line-of-sight attenuation (diffuse 2D-LOSA) was applied to measure soot volume fraction distribution in the flame. The influence of C0_2 dilution on flame appearance at various pressures was investigated. The quantity of soot formation decreases with the increase in C0_2 addition at all pressures, with the decrease rates being slower under higher pressure than lower pressure. With the addition of C0_2 to fuel side, the sooting zone decreases and tends to be concentrated toward the tip of flame. Generally, the overall soot temperatures of the C0_2 dilution flames decrease with increasing pressure and C0_2 addition, the most significant change in the lower and middle of the flame. At same pressure, the C0_2 addition has little impact on the flame height. As the pressure rises, however, the axial diameter of flame decreases to give an overall stretched appearance.