Flame extension lengths beneath an inclined ceiling induced by rectangular-source fires

The flame extension length beneath an inclined ceiling has not been studied in the past, and therefore no data or analysis is reported in the literature. Experiments were carried out in this work to measure both of the flame extension lengths in the upward and the downward directions beneath an inclined ceiling of different angles induced by rectangular fire sources with various heat release rates and source-ceiling heights. Results showed that the flame extension length was larger in the upward direction than that in the downward direction, which was physically explained as attributed to the non-symmetrical distribution of un-bunt fuel in the two directions after impingement. A new global equation was proposed to correlate the flame extension lengths in both directions by using modified non-dimensional heat release rates accounting for this non-symmetry. This work provided supplementary results over previous knowledge and correlations about flame extension beneath a flat ceiling.