Effect of ceiling extraction on the smoke spreading characteristics and temperature profiles in a tunnel with one closed end

A series of fire tests in a 1/15 scaled-model tunnel with one closed end have been conducted. Analysis was carried out to explore temperature distribution and smoke propagation under the influence ceiling extraction system. Five different heat release rates, three dimensions exhaust outlet, numerous rates were considered. Experimental results led some interesting findings about relationships between rate, fuel mass burning temperature. Two distinctive regions identified according their responses i.e., decay outlet almost independent rate while upstream decreased sharply increase rate. also conducted back-layering length, revealing its strong dependence on induced air velocity. Based experimental dimensional analysis, empirical formulas proposed capture length for tunnels utilizing extraction.