Abstract: Experiments were carried out in a one-third scale model of a twelve-storey stairwell in order to investigate the control effect of smoke spreading in the stairwell under different opening conditions. The fire source was located on the 6th floor. The smoke temperature distribution along the stairwell, the inflow or outflow velocity at the openings and the rising-time of smoke front under different opening conditions were discussed. The results show that the smoke temperature takes on an exponential decay along the vertical direction when the smoke reaches a certain height, and that the neutral plane height varies under various opening conditions. In general, when vents are opened on floors near the fire, smoke temperature decreases faster, the smoke spreads more slowly, and the effect of smoke control is better.

Key words: stairwell, stack effect, smoke control effect, vertical temperature distribution, neutral plane