A study on window plume from a room fire to the cavity of a double-skin façade

Double-skin façade (DSF) is a common feature in modern buildings. In case of a room fire, window may be broken and fire plume may be ejected into the cavity of the DSF. The plume behavior in such a particular space is an interesting problem in fire science and in applied thermal engineering. The objective of the present study is to determine the conditions under which the plume would attach to the interior or to the exterior skin. In this respect a simple theoretical model was proposed to calculate the net lateral pressure on the plume. Based on this theoretical steady-state model, window plume from a room fire ejected to DSF cavity was studied both experimentally and numerically using Computational Fluid Dynamics (CFD). A room-façade model rig was constructed with adjustable façade width. Different fuel supply rates to a propane burner were used in the experiment to yield different heat release rates. A total of 445 numerical simulations were carried out using the CFD-based software Fire Dynamics Simulator (FDS). Both experimental and simulation results show that for given cavity width, heat release rate and geometry of the window opening were the two key factors in determining the plume trajectory.