Experimental study on the effects of ventilation on smoke movement in tunnel fires

Abstract

ABSTRACTA reduced-scale temperature model was used to simulate Xiangshan Tunnel in experiments exploring the influence of vertical ventilation on the spread of smoke in tunnel fires. The results showed that the ambient temperature and vertical ventilation impacted the spread of smoke in a tunnel. A lower ambient temperature increased the speed of the smoke spread. A greater longitudinal velocity ensured that the flue gas spread downstream of the fire source, but the smoke also settled faster. Thus, the smoke layer could be destroyed, and the turbulence would endanger human evacuation. The theoretical and measured values showed satisfactory agreement for the critical smoke stratification speed. The maximum smoke temperatures near the tunnel ceiling with different horizontal distances from the fire source were also close to the values predicted by the Alpert formula. The test results indicated that ventilation greatly affected the temperature inside the tunnel, but increasing the wind speed did not further decrease the temperature. Further away from the fire source, ventilation had little effect on the temperature. Based on the experimental results, suggestions are provided for the management department to control the longitudinal velocity and perform an evacuation in the event of a tunnel fire.