Simulating Enclosure Fire Dynamics and Suppression
Howard R. Baum, Kevin B. McGrattan
At least three different physics based approaches to fire dynamicssimulations have evolved over the years; lumped parameter or ''zone models'',computational fluid dynamics models based on classical turbulence modelingtechniques, and large eddy simulations. Large eddy simulations provide themost realistic description of fire phenomena developed to date.All such simulations provide descriptions of the processes that controlthe mixing and combustion of fuel and air at elevated temperatures. In anenclosure fire these processes are complicated by the fact that the fuel wasinitially part of the building or its furnishings, and the air supply iscontrolled by the interaction of the fire with its surroundings. The geometryof the building and itsfurnishings all influence the fire and are in turn changed by it.Numerical models of fire suppression are dependent on the level of detailgiven to the combustion and fuel pyrolysis processes. Present models of gasphase suppression limited by the use of highly simpified models of combsutionmechanisms in large-scale simulations. Models of solid phase suppression arelimited by the lack of well-accepted, robust pyrolysis models that haveenough physical detail to accomodate the inclusion of water impingement.Several lumped parameter models of solid phase suppression by water havebeen developed over the past decade, but these models do not neccesarilywork well within a computational fluid dynamics framework. The key toimproving models of both fire dynamics and suppression phenomena is theinterface between the gas and solid phases. More physics is needed to properlydescribe solid phase suppression dynamics, and existing fundamentalcombustion models of gas phase suppression need to be simplified so that bothparts of the suppression problem can be brought into the same conceptualframework.
NRIFD Symposium-Science, Technology and Standards for Fire Suppression Systems
computer simulation, fire modeling, fire research, sprinklers, suppression