Experimental study on coupled combustion of PMMA counter-directional flame spread in the horizontal direction

An experimental study was carried out to address the effects of coupled combustion, and sample widths on counter-directional flame spread over poly(methyl methacrylate) (PMMA) boards in the horizontal direction. Typical flame propagation parameters were observed and analyzed, including flame form, flame front, charac-teristic angles, rate of spread, and radiative heat flux density. Experimental results showed that the counter -directional fire propagation process could be divided into four stages based on the flame morphology varia-tion, and the evolution of the flame front was presented as well. The characteristic angles, defined as half of the flame front angle, show the velocity variation between the side-edge and center flame at different spread phases. Compared with unilateral flame spread, the radiative heat flux density for the counter-directional flame spread grows faster, and the maximum value is about twice. Moreover, the maximal radiative heat flux increases for a wider sample, and a positive linear relationship exists between the dimensionless mass loss rate and charac-teristic angle against the breadth length ratio. The research outcomes of this study offer a better understanding of the counter-directional flame spread mechanism from aspects of scale change and heat transfer.

Automated summary

An experimental study was conducted to investigate the effects of coupled combustion and sample widths on counter-directional flame spread over PMMA boards. Flame propagation parameters, including flame form, flame front, characteristic angles, rate of spread, and radiative heat flux density, were observed and analyzed. The study found that the counter-directional fire propagation process can be divided into four stages based on flame morphology variation, and the evolution of the flame front was described. Compared to unilateral flame spread, the radiative heat flux density for counter-directional flame spread increases faster, reaching a maximum value of approximately twice. The research outcomes provide a better understanding of the counter-directional flame spread mechanism in terms of scale change and heat transfer.