Effect of guide vanes on recovering uniform flow in a ventilation duct in an existing twin-track subway tunnel

The steady three-dimensional airflow in a subway tunnel was analyzed using ANSYS CFX software by solving Reynolds-averaged Navier-Stokes equations. A ventilation system in a model subway tunnel was developed by analyzing the mass flow rate through the ventilation shafts and the airflow in the tunnel. The airflow in the tunnel and mass flow rate in the shafts were investigated with a guide vane, porous zone, and air-curtain installed in the subway model tunnel. A mechanical shaft of an existing subway tunnel in Seoul was analyzed to apply the developed ventilation system to the tunnel. The ducts of the mechanical shaft were connected in two different ways, and guide vanes were installed in the shafts. An emergency duct between the ducts of the mechanical shaft was used to connect the ducts and install the precipitator. An axial flow fan in the duct was used to induce swirling flow. Guide vanes were installed at one side and both sides of the shaft before the electric precipitator to obtain uniform flow, which enhances the performance of the precipitator. A proper duct connection for higher mass flow rate was obtained. The installation of guide vanes on both sides led to more uniform flow in the duct. The developed ventilation system was applied to the actual subway tunnel by connecting ducts and installing the guide vanes on both sides of the ducts.