An experimental investigation and correlation on buoyant gas temperature below ceiling in a slopping tunnel fire

Abstract

The effect of tunnel slope on the fire induced hot gas temperature profile beneath the ceiling has not been clarified nor included in existing models. Thus, in this paper experiments are carried out in a reduced scale model tunnel with dimensions of 6 m (length) × 1.3 m (width) × 0.8 m (height), which is positioned within a 72 m long wind tunnel. The slopes of the model tunnel are varied at three typical different degrees, 0%, 3% and 5%. A LPG porous gas burner is used as fire source. Both the maximum gas temperature and the temperature distribution along the tunnel ceiling are measured and compared with previous models. Results show that those models overestimates the maximum temperature beneath the ceiling of a slopping tunnel fire. The gas temperature decays faster along the ceiling for tunnels with higher slope. Empirical correlations are then proposed to modify the current models to include the tunnel slope factor. The predictions by the modified equations of this work agree well with the measured data in both the maximum temperature and temperature decay beneath the ceiling of the tunnel with different slopes.