Measurements of the Wake Flame Behind a Sphere via Raman Scattering

Abstract

An experimental study was conducted on the structure of the wake flame formed behind a porous sphere from which methane was discharged into a uniform stream of dust-free dry air. Laser Raman scattering was applied to measure the temperature and the number densities of gaseous molecules in the flame. Flame thermometry was based on the measured results of the Stokes-Raman spectrum of the nitrogen molecule which was subjected to the monochromatic irradiation of the argon laser (488nm). The chemiluminescence emission spectra of the flame were also measured. The results showed that the maximum temperature was observed near the periphery of the visible flame. The ratio of the number densities of oxygen to nitrogen molecules in the central portion of the flame was much lower than the value in room air. Strong OH emission was observed near the maximum-temperature region.