Transient three-dimensional fire-induced air flow in a full scale ventilated tunnel

Abstract

A modified three-dimensional version of the turbulence k - ε model is applied to simulate the transient fire-induced air flow and smoke movement in a full scale ventilated tunnel. The model adopts the general curvilinear coordinate system to preserve the actual geometry of the tunnel. A modified elliptic grid generation method is introduced to specify all of the boundaries in terms of grid distribution, grid size and angle of intersection. The effects of the buoyancy and mean streamline curvature on turbulence are accounted for in the model. The smoke concentration is expressed in terms of smoke obscuration and is calculated by a conservation equation. The QUICK discretization scheme is used. The predictions are shown to be in reasonable agreement with reported experiment data. Application of the mixed convection parameter Gr*/ReH 5/2 has been extended and this is confirmed by the observed temperature stratification of the heated air flow in the full scale tunnel.