Measurements of temperature and OH radical distributions in a silica generating flame using CARS and PLIF

Distributions of flame temperature in silica generating coflow diffusion fl ames have been measured using coherent anti-Stokes Raman spectroscopy (CARS ) and qualitative measurements of OH radical concentrations have been made utilizing planar laser-induced fluorescence (PLIF). Silica particles have b een visualized through the plane images of light scattering from particles. The results show that aerosol generation due to chemical reactions can sig nificantly affect thermal and chemical characteristics of hydrogen-oxygen d iffusion flames. When SiCl4 is added to a flame, the temperature in non-rea cting zone decreases due to the increases in both specific heat and density of the gas mixture while the flame temperature increases in the particle f ormation zone due to exothermal chemical reactions of hydrolysis and oxidat ion of SiCl4. It has also been Found that OH concentration decreases dramat ically in the particle formation zone, which can be attributed to both the generation of HCl and the consumption of O-2 and H2O during silica formatio n. (C) 2001 Elsevier Science Ltd. All rights reserved.