This experimental study is motivated by the progress of hot,toxic,products during a fire in a high-rise building.The experiments involve a 2.6 m tall square shaft with various cross sections and openings.The shaft was situated above a large temperature controlled hot air reservoir that was separated by a cooled sliding gate.At the start of the experiment the gate was opened in a rapid horizontal motion and the hot and cold gases are allowed to mix.For the shafts with openings,the gases are withdrawn from apertures at different rates.The temperature of the gas and wall,and heat transfer to the wall is measured as functions of time at five different elevations in the shaft.At each elevation measured,the cross-section averaged gas temperature,reached and fluctuated about a steady state value soon after the initial front of hot gas arrived at that location.The time averaged heat transfer coefficient was weakly dependent on both the initial reservoir temperature and flow-rate.The experiments also indicated that the front propagation times are significantly affected by openings in the shaft.
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