In situ measurements of oxide particles in boron-containing diffusion flames

✍ Scribed by S.R. Turns; M.J. Funari; A. Khan

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 884 KB
• Volume: 75
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(89)90096-5

✦ Synopsis

Particulate matter in axisymmetric laminar diffusion flames produced by burning mixtures of either CO and trimethylborate (TMB) or CI-h and TMB with air were investigated using laser light-scattering techniques. Boron oxide particle sizes and number densities were determined at various heights in the flames using polarization ratio and relative intensity measurements, respectively. In the CO/TMB flames, two distinct particle-laden regions were found. The first region was located on the rich side of the luminous flame zone and initially appeared as a narrow annulus, which grew in width downstream until the particles filled the core. A second thin annular zone appeared on the air side of the flame zone, starting approximately at the height of the luminous green flame tip and continuing to grow downstream. Particle sizes did not vary significantly with location in the flames, with diameters of approximately 0.09 and 0.15 #m in the 95% CO/5% TMB and 90% CO/10% TMB flames, respectively. Corresponding peak number densities were approximately 1.5 x 101° and 6 × 109 cm-3o The CH4/TMB flames were considerably different than the CO/TMB flames. The presence of significant quantities of water vapor presumably contributed to the formation of HBO2(g) in favor of condensed-phase 13203. At locations where oxide particles did form, they were closer to the flame centedine than the soot-containing regions. Computations of equilibrium yields of condensedphase oxide were in qualitative agreement with the experimental results.