Investigations on Soot Formation in Heptane Jet Diffusion Flames by Optical Techniques

Two-dimensional optical measurements were performed for the investigation of soot formation of n-heptane laminar gas-jet diffusion flames under buoyant and non-buoyant conditions utilizing the Bremen Drop Tower. Techniques employed were laser-induced incandescence for the determination of soot concentration and primary particle sizes and two-color emission pyrometry with a three-point Abel inversion for the measurement of temperature fields. In line with former experiments for other hydrocarbon fuels the investigations revealed drastic differences in the sooting behavior between flames under normal and microgravity. With the lack of buoyancy maximum soot temperatures were reduced by roughly 300 K and maximum primary particle sizes were more than doubled.