Experimental study of the influence of interior lining distributions on flashover in the enclosure with different ceiling structures

Different distributions of interior linings in an enclosure have been studied to reveal the influence on time to flashover. Two kinds of ceiling structures, flat ceiling and flat ceiling with beams, were used for enclosure. Six full-scale experiments were performed to investigate the occurrence of flashover in large enclosures. Heat release rate, gas temperature, and surface temperature of the enclosure were measured and analyzed. Experimental results show that time to flashover is extended for enclosure with large surface areas and large doors. Whether lining the interior linings on the ceiling or beams has a significant effect on flashover. Considering that ceiling fires have effect on the progress of the spread of flame on the wall, time to flashover is reduced for the tests that are fitted with the interior linings on the wall of the enclosure. In the enclosure with beams, the direction of spread of flame on the ceiling is changed, resulting in the change of time to flashover. Additionally, the strength of ceiling jets that is affected by the heat release rate of fire source and the area of the interior linings mounted on the fire source influenced region affects flashover. It is observed that flashover occurs when flame fronts are throughout the upper part of the back wall and the flame-covered area on the back wall exceeds 0.2 times the area of the back wall.