Experimental study on the variation regimes of window ejecting flame height

The fast growth of window ejecting flame height has long been thought to be influenced by the vertical wall via partially blocking air entrainment on the by-wall side. In the present research, experiments were conducted by employing a reduced scale compartment-façade model to examine this view and study the factors leading to the fast flame height growth. The inner size of the compartment was 0.4 m (W) by 0.6 m (L) by 0.4 m (H). A 0.2 m by 0.2 m square propane burner was employed as a fire source. Flame height in cases with and without vertical wall were compared. It was shown that in cases both with and without vertical wall, the flame height underwent a rapid growth with increase of heat release rate (HRR) Q when 1.8 ≤ Q/Q_c ≤ 2.5, where Q_c is the theoretical maximum HRR inside the compartment and Q/Q_c is a dimensionless HRR. The rapid growth of flame height was mainly caused by the increase of combustion efficiency rather than the vertical wall. The growth of flame height showed a power-law dependence on Q/Q_c. The power index was 0.8, 2.5, and 0.8 for the ranges 1 ≤ Q/Q_c ≤1.8, 1.8 ≤ Q/Q_c ≤ 2.5, and Q/Q_c ≥ 2.5 respectively.