Re-visiting NIST Reduced/Full-Scale Enclosures (R/FSE) Experiments (2007-2008)

In post-flashover compartment fires, it is advantageous to understand the effect that vertical opening locations have on the heat fluxes experienced from the external fire plumes, because it is a crucial parameter to understand the potential risk in urban fire spread. In this paper, a Reduced (40% scaled ISO-9705 room) and Full-scale (ISO-9705 room) enclosure were used to demonstrate computationally the effect of the window location relative to the door. A parametric study was done using validated cases for a Computational Fluid Dynamics (CFD) Code namely Fire Dynamics Simulator (FDS) with 19 and 14 different window locations for the Full and Reduced scale experiments, respectively.
The primary Full-scale parametric study showed that the location of the window played an important role in the heat flux values from the door and the window, where it was found that the heat flux from the vertical openings could decrease by as much as 60% or increase by up to 30% based on the location of the window relative to the door. In this study the optimal location of the window, relative to the door, on each wall was demonstrated, i.e. for the front door it is safer to place the window further away from the door, while for the side walls it is safer to place the window closer to the front wall, and for the back wall it is safer to place the window opposite to the door. The reduced scale study showed good correlation to the full-scale for the front and back wall cases, however, it failed to replicated those for the side walls.