Experimental study on flame spread behavior along poly(methyl methacrylate) corner walls at different altitudes

The effects of altitude and intersection angle on the flame spread behavior and pyrolysis front characteristics along corner walls were experimentally studied. The experiments were conducted using mock corners made of poly(methyl methacrylate) slabs with intersection angles varying from 60 degrees to 120 degrees at two altitudes of 29.8 and 3658.0 m. Measurements were taken for the upward and lateral flame spread rates, the flame heights, the flame heat flux to the fuel surface, and the mass loss rates of the tested slabs. An M-shaped pyrolysis front was observed for all the intersection angles examined at both altitudes. The upward flame spread rate increases with decreasing intersection angles while no obvious trend was found for lateral spread rate when the intersection angle is varied. The high altitude leads to a spread rate about half of that at the lower altitude both for upward and lateral spread irrespective of the intersection angle. The measured mass loss rates are significantly higher than twice of that over a flat vertical slab.