Synergistic effect of fire location and vent setting on the smoke control in tunnel fires with point extraction ventilation
This paper investigated the synergistic effect of longitudinal fire location and vent size on the smoke control in the tunnel fire with point extraction ventilation based on 1:10 reduced-scale experiments,numerical simulation,and force analysis of the smoke beneath the vent.Different Heat Release Rates(HRRs),longitudinal fire locations,and vent lengths were also considered.Results show that the critical exhaust rate is not equal to the fire moving away from the tunnel center.The critical exhaust rate is the required exhaust rate of the near-fire vent for a vent length of less than 0.10 m.This is because the horizontal inertia force induced by the heat pressure is strong when the vent length is small.On the contrary,the critical exhaust rate refers to the required exhaust rate of the far-fire vent when the vent length exceeds 0.10 m.This phenomenon results from the smoke in the smoke extraction channel flowing to the far-fire vent,which results in the decrease of the actual exhaust rate of the far-fire vent.Overall,the critical exhaust rate increases with a fire gradually deviating from the tunnel center and decreases with increasing vent length.However,excess vent length can bring an adverse effect on smoke control from the perspective of critical exhaust rate.This is attributed to a large amount of fresh air being exhausted through the large vent,resulting in a decrease in smoke extraction efficiency.Experimental results illustrate that the critical vent length is 0.15 m.Besides,from the view of smoke control,a worst longitudinal fire location related to the vent length is proposed in this paper.Experimental results suggest that the worst longitudinal fire location is C when the vent length is less than 0.15 m,while the worst longitudinal fire location is D when the vent length is more than 0.15 m.
safety engineeringtunnel firepoint extraction ventilationthe worst fire locationcritical vent length
万方数据
维普
