Boundary Conditions for Three-Dimensional Simulation of Fires in a Railway Emergency Rescue Station

For fire safety emergency rescue stations are commonly set up in the twin-tube railway tunnels longer than 20 km. Three-dimensional simulation of fires in an emergency rescue station is useful to evaluate the effectiveness of the emergency ventilation system. The determination method of the boundary conditions of three-dimensional simulation of a railway emergency rescue station was given, and the effect of local resistance coefficients and fire source location on the boundary conditions was analyzed. Numerical results shows that the cross-passages could be equivalent to a single tube, and the local resistance coefficients of the single tube are so small compared with the frictional resistant coefficients of the tunnels that the local resistance coefficients have little effect on the boundary conditions. And the boundary conditions and the total flux of the nine cross-passages are almost invariant with the fire source location at a given flux of air supply and exhaust.