Effects of ceiling inclination on lateral flame spread over vertical Poly(methyl methacrylate) surface

A series of experiments was designed to investigate the effects of ceiling inclination on lateral flame spread over vertical poly(methyl methacrylate) (PMMA) surface. PMMA slabs with width ranged from 3 cm to 9 cm were tested at the ceiling inclination from 30° to 90°. Burning rate, flame spread rate, and flame appearance were investigated experimentally. The results suggest that in the cases of narrow PMMA slabs, the flame spread rate presents a “U” variation with the increasing ceiling inclination. But flame spread rate of wider slabs decreases with ceiling inclination. Burning rate follows a power-law change with the sample width, which is m˙/W∝W0.136−0.421sin(α). And the exponential relationship between pyrolysis length, sample width and ceiling inclination can be given as xp∝W0.455−0.16sin(α).