MD2-3: Investigation of Soot Formation in the Oxygenated Fuels Flame by Laser Induced Fluorescence and Incandescence(MD: Measurement and Diagnostics,General Session Papers)

It is reported that the oxygenated fuels play significant roles in reducing soot emission. However, the mechanisms of soot formation and oxidation in oxygenated fuels and conventional diesel fuel so far have not been well understood. Laser induced incandescence (LII) is particularly suited to measure the instantaneous spatial distribution of the soot volume concentration, which can offer much needed detailed information of soot distribution for better understanding of soot formation and oxidation. In this paper, a two-color laser induced incandescence (2C-LII) technique was implemented for measuring absolute soot volume fraction in a laminar diesel fuel diffusion flame. Based on LII signal of the same point in the flame recorded at two wavelengths, the temperature of the laser-heated soot particles was first derived and later the soot concentration of the point was acquired by calibration. The 2D soot concentration distribution in the flame was obtained by mapping. The 2D concentrations of polycyclic aromatic hydrocarbons (PAHs) which are main precursor of soot were obtained by laser induced fluorescence (LIF). Measurements were performed in a laminar diesel and biodiesel/air diffusion flame by 2C-LII and LIF. It was found that with the biodiesel blended in the diesel fuel, the maximum soot and PAHs concentration decrease as well as their distribution area.