Experimental Study on the Influence of Fire Source Elevation on Smoke Temperature Profile Driven by Buoyancy in a Full-scale Mountain Tunnel

Abstract

ABSTRACT Previous studies have not sufficiently focused on the fire characteristics of different fire source elevations in a longitudinal ventilated tunnel fire, especially for a full-scale tunnel. In this work, a set of full-scale burning experiments were conducted to investigate the maximum temperature under the ceiling and longitudinal hot smoke temperature decay characteristics by considering the effect of heat release rate (HRRs), ambient wind velocity, and fire elevation. Experimental results show that the maximum temperature profile under the tunnel ceiling is mainly dependent on the interactions of HRRs, wind velocity, and fire elevation. The comparison of the maximum temperature model predicted by previous studies with these experimental data was conducted, which demonstrates that Li’s model is more appropriate to describe the maximum temperature under the ceiling. Moreover, the dimensionless longitudinal temperature decay rate of hot smoke induced by fire exhibits an obvious increasing trend with the fire elevation increases. A modified model of longitudinal temperature profile along the tunnel ceiling was put forward by considering the effect of fire elevation. The current work will provide some references for fire protection design and arrangement of alarm devices in an ambient ventilated tunnel fire caused by different vehicle heights.