Pressure Modeling of Transient Crib Fires

Abstract

Abstract-It has previously been demonstrated that free burning fires in solid fuels can be modeled by increasing the ambient air pressure while reducing all length scales with the two-thirds power of pressure. The modeling concept has been tested, up till now, for steady or quasi-steady aspects of fires in simple, isolated fuel elements of wood or solid plastic. The current study is concerned with testing the pressure modeling concept for the important transient processes of fire growth and decay in pine-wood cribs ignited at the center of the crib base. In addition, the validity of pressure modeling compartment fires is tested by burning cribs within simplified, vented enclosures. Measurements of crib burning rates for a ten to one range of length scale show that pressure modeling of portions of Ihe burning rate time history is indeed easible. While modeling of ventilation-controlled crib fires is highly successful, it appears that a lack of modeling of the rate of radial fire spread within the crib allows only peak burning rates and the fire decay process to be modeled in the fuel surface-controlled regime. For the specific crib geometries considered, the effect of an enclosure on fire intensity is measurable and can be pressure modeled.