Investigating the Impact of Opening Size on Fire Spread Across Vertical Exterior Surfaces

This study examined the risk of vertical fire spread on exterior walls subjected to flame ejection by measuring temperature and heat flux during real-scale fire experiments. The fire experiment was conducted in a mock-up measuring 2.4(L) × 3.6(W) × 2.4(H) m. Wood cribs were used as the combustible material, and heptane as the initial ignition source. The mock-up featured two singular openings of different dimensions, 2.2(L) × 2.0(H) m (#1) and 2.2(L) × 1.0(H) m (#2), on its front side. Temperature and heat flux variations were measured at the upper part (0.0 m) and on the exterior upper wall (0.5 and 1.0 m) of the mock-up. The maximum heat flux was 15.0 kW/m2 at location #1 and 42.4 kW/m2 at location #2. The maximum temperature was 291.0 ℃ at location #1 and 626.4 ℃ at location #2. This study examined the burning rate of the compartment and the impact of the opening size on the radiant heat and temperature of the exterior walls.