Experimental Studies on a Rise-Time of Smoke Layer Interface in Vertical Shaft

The present paper is engaged in an experimental study over a rise-time of smoke layer interface and deduced the relation between dimensionless rise-time of smoke layer interface and dimensionless height of the shaft. Based on the theoretical results, the risetime of smoke layer interface is measured by using small scale shaft which are located at the PolyU/USTC Atrium. Our study shows that the rise-time of the smoke layer interface be inversely proportional to the 1/3 power of heat release rate of the fire source, and proportional to the 1.05 and the 1.50 power of the height in open and closed shafts, respectively. Furthermore, it is also proved that the smoke layer interface movement in open shaft be faster than that in a free space and closed shaft due to the stack effect. Under the same fire source and shaft dimensions, the velocity of smoke spreading in closed shaft is the least one.