Figure 2.8 listed situation of the fire in a floor near to the atrium at the beginning of fire. The fire floor has 2 vertical vents open to the atrium and to ambient at outside. The atrium is apen from the top.
At the beginning of fire , the smoke moves to outside and the atrium, and air from ambient and the atrium moves inside the fire floor at the same time from the 2 vents. Figure 2.8 shows the velocity direction at the vents. At the top of the vents, because the smoke in the fire floor is lighter than the air in the atrium and ambient because of the high temperature, pressure difference between the fire floor and atmospheric pressure is larger than at the lower place of the vents. At the bottom of the vents, the pressure difference becomes negative to that at the top. So there should be neutral pressure plane or …show more content…
Heat will be moved from the hot smoke to the descending cold air and from smoke to the atrium walls. Then if the cross sectional area of the atrium is small and the HRR of fire is high enough, smoke column will be created and flooding flow will occur in the atrium, too. In other hand, if the cross sectional area of the atrium is high and the HRR of fire is small, smoke column will not create in the atrium and floding flow will not occur to vent smoke. Figure 2.8 Flow at the early stage of adjacent floor fire[13].
Table 2.4 Conditions of each simulation [13]. By watching the calculation results dynamic display, then the time and location of the flooding flow can be obtained.Floding flow did not occur till the simulation end time at 800 second in the atria with size 11×11×27m and 12×12×27m. In the range of designed HRR of fire (100 kW to 2000 kW), HRR of fire in most cases had no effect to whether flooding flow occurs or not, but it affected the time when it became
At the beginning of fire , the smoke moves to outside and the atrium, and air from ambient and the atrium moves inside the fire floor at the same time from the 2 vents. Figure 2.8 shows the velocity direction at the vents. At the top of the vents, because the smoke in the fire floor is lighter than the air in the atrium and ambient because of the high temperature, pressure difference between the fire floor and atmospheric pressure is larger than at the lower place of the vents. At the bottom of the vents, the pressure difference becomes negative to that at the top. So there should be neutral pressure plane or …show more content…
Heat will be moved from the hot smoke to the descending cold air and from smoke to the atrium walls. Then if the cross sectional area of the atrium is small and the HRR of fire is high enough, smoke column will be created and flooding flow will occur in the atrium, too. In other hand, if the cross sectional area of the atrium is high and the HRR of fire is small, smoke column will not create in the atrium and floding flow will not occur to vent smoke. Figure 2.8 Flow at the early stage of adjacent floor fire[13].
Table 2.4 Conditions of each simulation [13]. By watching the calculation results dynamic display, then the time and location of the flooding flow can be obtained.Floding flow did not occur till the simulation end time at 800 second in the atria with size 11×11×27m and 12×12×27m. In the range of designed HRR of fire (100 kW to 2000 kW), HRR of fire in most cases had no effect to whether flooding flow occurs or not, but it affected the time when it became