The Characteristic Analysis of Fire-Driven Flow Simulation Code (FDS) for Railway Tunnel

초록

The performance and applicability of FDS code is analyzed for flow simulation in railway tunnel. RANS and DNS's results are compared with FDS's. AJL non-linear model is employed to calculate the turbulent flow for RANS. DNS data by Moser et al. are used to prove the FDS's applicability in the near wall region. Parallel plate is used for simplified model of railway tunnel. Geometrical variables are non-dimensionalized by the height (H) of parallel plate. The length of streamwise direction is 50H and the length of spanwise direction is 5H. Selected Re numbers are 10,667 for turbulent flow and 133 for laminar low. The characteristics of turbulent boundary layer are introduced. AJL model's predictions of turbulent boundary layer are well agreed with DNS data. However, the near wall turbulent boundary layer is not well resolved by FDS code. Half-Slip (default) conditions are imposed on the wall but wall functions based on log-law are not employed by FDS. The heavily dense grid distribution in the near wall region is necessary to get correct flow behavior in this region for FDS.