Effect of shaft height on smoke control in tall building fires

Smoke exhausting through shaft from fire room with an opening was theoretical analysed and numerical simulated. The critical shaft height to control smoke not overflowing the fire room was induced. The influence of shaft height on the variation trend of pressure, velocity and temperature in shaft and air supply opening as well as indoor temperature was studied. With the increase of shaft height, the static pressure difference between the top and bottom of the shaft increases, so the stack effect is more obvious, and the smoke spillage from fire room through opening decreases, therefore the smoke can be controlled effectively and confined within the room finally. That is to say, under certain conditions, when the shaft height reaches a certain value, the smoke does not overflow. And on the other hand, the stack effect increases continuously until it reaches a critical state, so the stack effect also has another critical state with the increase of shaft height. The results of theoretical analysis and numerical simulation agreed well.