A smoke exhausting method through a baffle-coupled shaft during tunnel fires

Abstract In natural ventilation of road tunnel shaft, the plug-holing and boundary layer separation will decrease the efficiency. A new concept (baffle-coupled shaft) is put in place to solve the difficulty. Install baffle on both sides of the shaft (when the fire occurs upstream of the shaft, the baffle upstream of the shaft closes and the baffle downstream of the shaft opens), in the early stage of the fire, it can function as a smoke barrier. Numerical simulation was performed using the Fire Dynamic Simulation (Version 5.5.3). We use the mass flow of carbon monoxide discharged through the shaft as a basis for evaluating the efficiency of exhausting smoke. We could have determined that with the height of the baffle increasing, so does the efficiency of exhaust. In the investigation, the height of urban road tunnels is generally about 5 meters. So, it is appropriate to set the baffle height to 2m. Comprehensive car capacity, economy and cold air distributed, we can get a better He, that is in 1.0-1.5.