Vertical flame spread with horizontal projection

This report consists of two main parts. The first part focuses on the results from several smallscale experiments. A vertical and combustible wall was exposed to external venting flames from a lower compartment. A non-combustible horizontal projection was used to reduce the direct impingement of the venting plume on the wall. The wall consisted of particle board and the horizontal projection was made of calcium silicate. The effectiveness of the horizontal projection in preventing vertical fire spread along the wall was studied for six different heatrelease rates (33, 37, 42, 47, 51 and 56 kW). The study investigated how different projection sizes impacted flame height, ignition, vertical temperature development, and char formation. In this study, 0.075 m and 0.1 m projections were used principally, while other projections (0.05 m and 0.2 m) were used for specific cases. The 0.1 m projection was more effective in reducing vertical flame heights and temperature development compared with the 0.075 m projection. The 0.1 m projection successfully prevented ignition on wall at 33 kW and 37 kW fires during the 10 min experimental duration, while the 0.075 m projection prevented ignition at 33 kW fire only. However, at higher heatrelease rates, the wall ignited with both projections. Once ignition occurred, flame spread across the wall surface due to the combined effect of the burner and combustible gases from the pyrolysis process. The flame spread decreased after char formation on the wall. Char area and depth increased with higher heat-release rates for both projections, although there were no significant changes in vertical char height. A longer projection (0.2 m) was more effective by preventing ignition against 47 kW fire. The longer deflection distance restricted continuous attachment of flames and heat transfer to the wall. The second part of this study involves a computational simulation study. A three-storey building model was constructed using the FDS software ‘PyroSim’, where the flame started at the bottom compartment. A 3.1 MW fire was simulated and spread to the upper floors through the window. Two types of projections of variable lengths (0, 0.4, 0.6, and 0.8 m) were placed over each floor. One projection type was an open-ended ceiling projection, while the other one was solid wall balustrade (such as balcony with railing). The exterior wall or façade of the building, along with the projection didn’t include any combustible material. The simulation study allowed visualization and comparison of the flame trajectory and thermal behaviour of the ascending plume as it interacted with each projection type. Both projection types of several lengths (0.4 m, 0.6 m and 0.8 m) effectively reduced thermal impact, by 39% to 91%, on the upper floors compared with no projection, while the reduction increased with projection lengths. However, the temperature distribution at upper floor walls was affected by the projection types and lengths. Additionally, the thermal impact on a nearby building was also studied in these fire scenarios.