An Experimental Study on Buoyant Spilled Thermal Plume Temperature Profile from Over-ventilated Enclosure Fires in a Reduced Air Pressure

Abstract

To investigate the effect of a reduced air pressure condition on buoyant spilled thermal plume temperature profile from over-ventilated enclosure fires, the same scale model experiments were performed correspondingly in both Hefei city (altitude: 50 m, ambient pressure: 1 atm) and Lhasa city (altitude: 3650 m, ambient pressure: 0.64 atm). Comparative experimental results for both the lateral (normal to façade) and vertical (along facade) spilled plume temperature profile show that the lateral decay of temperature in the reduced air pressure is much faster than that in the normal air pressure condition. Meanwhile, the normalized spilled thermal plume temperature near the façade wall is much higher in the reduced pressure atmosphere than that in the normal pressure condition at the same height, indicating possibly weaker air entrainment of the buoyant spill plume in reduced pressure. These results reveal that fire safety regulations to counteract the vertical fire spread to upper floors need to be specified more rigorous at high altitude.