Level Environmental Wind Under The Plume Mass Flow Rate

Smoke has been found to be the main cause of death in fire accidents.The smoke production rate determines the criticality of fire, which is described by combustion rate and mass flow rate above the fire source, it plays a vital part in the structural design of fire protection and detection. While most studies about the fire plume has been studyed in no-wind conditions, most fire accidents in fact occur in surrounding wind conditions, which have great impact on the mass flow rate of plume. This paper concludes the findings of mass flow rate under surrounding wind, based on dimensional analysis and numerical simulation.(1) Based on numerical simulation, this paper concludes the relationship between mass flow rate and surrounding wind, that is, as the efficiency of heat release of fire increases, the critical wind velocity would increase, which in turn maximizes the mass flow rate plume.(2) Based on theories of plume and jet in cross flow, this paper suggests that under surrounding wind conditions, the structure of fire plume could be divided into three regions, namely: The region of core potential flow, the region of plume bending and the region of throughout plume.(3) The inclination angle formula of fire plume is explored, based on assumptions of the plume's structure and horizontal section under surrounding wind condition.(4) Utilizing dimensional analysis, formulas for the orbit and velocity of jet in cross flow and plume and the assumptions of the plume's structure and horizontal section, a model for the mass flow rate of plume under surrounding wind conditions is established. The undetermined coefficients are found using the Non-linear fitting, based on simulated results.