Sooting behavior on a spreading flame over PMMA rods under different oxygen concentrations

The flame spread process over the surface of a solid combustible material is highly influenced by the radiative feedback from the flame, and the conditions under which the process takes place. Soot particles generated during the burn are a big contributor to flame radiation and can play a critical role in the radiative exchange between the flame and the solid. Thus, increased knowledge of the soot production processes involved in the spread of a flame can further promote the understanding of growth and development of fires. The main purpose of this work is to study the effect of oxygen concentration on the sooting behavior of cylindrical samples of polymethyl-methacrylate (PMMA) in an opposed flow configuration. Measured data shows that during downward/opposed flame spread the mass burning rate and soot volume fractions increase with higher oxygen concentrations. The data presented is correlated using a scaling analysis that provides correlations for the maximum soot volume fraction, and the maximum integrated soot volume fraction as a function of the oxygen concentration using similar residence times to establish comparable conditions. The data shows the correlations introduced here provide useful information of the sooting behavior of spreading flames in environments of varied oxygen concentrations that could be used to guide potential fire safety applications.