An experimental study was conducted to investigate the thermal, chemical, and flow environments of heptane fires in an ISO 9705 room. Fuel flow rates and vent size were manipulated to create overventilated fire (OVF) and underventilated fire (UVF) conditions. Numerical simulations were also performed, for the same conditions, with the Fire Dynamics Simulator (FDS) developed at the National Institute of Standards and Technology. Both OVF and UVF conditions were characterized with temperature distributions, and combustion product formation measured locally in the upper layer, as well as combustion efficiency and global equivalence ratio. It was shown that the numerical results agree quantitatively with measurements in both OVF and UVF. The internal flow pattern rotated in the opposite direction for the UVF relative to the OVF so that a portion of products recirculated to the inside of compartment. This flow pattern may affect changes in the complex processes of CO and soot formation inside the compartment due to an increase in the residence time of high-temperature products. The 3D flow structures including O₂ and CO distribution were visualized inside the underventilated compartment fire using FDS. It was observed that the two gas sample locations in the upper layer of the room were insufficient to completely characterize the internal structure of the compartment fire.

An experimental study was conducted to investigate the effects of fuel location and distribution on full-scale underventilated compartment fires in an ISO 9705 room. Heptane fuel was burned in three different fuel distributions: single centered burner (SCB), single rear burner (SRB), and two distributed burner (TDB). It was experimentally observed that variations in fuel placement did not significantly affect the global steady state underventilated fire characteristics such as fuel mass loss rate, heat release rate, combustion efficiency, global equivalence ratio, and global CO emission outside the compartment for these simple distributions. Supplemental numerical simulations reveal that the local characteristics of thermal and chemical environments depend on the fuel placement between the front and rear region inside the compartment. At the front region, the local fire characteristics were nearly the same regardless of fuel placement. Changes in fuel location and distribution resulted in changes in temperature, total heat flux, CO₂, and CO volume fraction at the rear region. Burner placement led to changes in the mixture fraction, flow dynamics, and variations in CO production in the back of the compartment.