It is known that there is a lag time for smoke plume induced by fires transporting from a fire origin to the location of interest underneath an unconfined and flat ceiling.This lag behavior of smoke plume also exists ...It is known that there is a lag time for smoke plume induced by fires transporting from a fire origin to the location of interest underneath an unconfined and flat ceiling.This lag behavior of smoke plume also exists for a fire under a sloped ceiling,and is fundamental to estimate the activation time of a fire detector or other fire extinguishing system.This study focuses on the lag time of smoke plume under a sloped ceiling.Based on the weak-plume theory at early-fire phase and previous studies concerning the fire plume characteristics under a sloped ceiling,a calculation method on lag time of fire plume transporting is presented in theory.Meanwhile,two dimensionless equations predicting the lag time of fire plume for steady fire and unsteady fire are proposed respectively.Furthermore,the critical time calculation equation is also proposed to determine the applicability of quasi-steady assumption for a time-dependent fire.展开更多
An investigation on the scenarios of the spill plume and its equation was presented,including two aspects,i.e.,the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by co...An investigation on the scenarios of the spill plume and its equation was presented,including two aspects,i.e.,the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the fire dynamic simulation (FDS) and small scale model experiment results. Besides validating the spill model by experiments,the effect of different fire locations on balcony plume is also discussed. The results show that the balcony equation in NFPA gives good predictions on the mass flow rate. And the balcony plume entrainment coefficient is independent of the fire location. This investigation is useful for the fire engineers in designing smoke control systems.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.50909058)"Chen Guang" Project of Shanghai Municipal Education Commission and Shanghai Education Development Foundation Science&Technology(Grant No.10CG51)
文摘It is known that there is a lag time for smoke plume induced by fires transporting from a fire origin to the location of interest underneath an unconfined and flat ceiling.This lag behavior of smoke plume also exists for a fire under a sloped ceiling,and is fundamental to estimate the activation time of a fire detector or other fire extinguishing system.This study focuses on the lag time of smoke plume under a sloped ceiling.Based on the weak-plume theory at early-fire phase and previous studies concerning the fire plume characteristics under a sloped ceiling,a calculation method on lag time of fire plume transporting is presented in theory.Meanwhile,two dimensionless equations predicting the lag time of fire plume for steady fire and unsteady fire are proposed respectively.Furthermore,the critical time calculation equation is also proposed to determine the applicability of quasi-steady assumption for a time-dependent fire.
基金Project(CN/ASIA-LINK/011(91-400)) supported by European Community Asia-link Project Centre of Sino-European Sustainable Building Design & Construction
文摘An investigation on the scenarios of the spill plume and its equation was presented,including two aspects,i.e.,the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the fire dynamic simulation (FDS) and small scale model experiment results. Besides validating the spill model by experiments,the effect of different fire locations on balcony plume is also discussed. The results show that the balcony equation in NFPA gives good predictions on the mass flow rate. And the balcony plume entrainment coefficient is independent of the fire location. This investigation is useful for the fire engineers in designing smoke control systems.
