This theoretical paper studies of the interaction between air curtains system and purging dilution systems in a real urban underground railway station in order to find the best design to reduce concentration of polluting gas toward adjoining environments. Numerical computations are carried out with NIST package Fire Dynamics Simulator (FDS). The use of an approximate form of the Navier-Stokes equations for low Mach number application is appropriate. Polluted gasses flow towards safe space can be reduced of the 26-53% by operating air curtain systems.
This paper aims at showing the difference between the two approaches used to evaluate the capture efficiency of a local ventilation system : an experimental research using the tracer gas method ( CO2) and the numerical modelling using CFD code ( STAR-CD). Comparison between the two methods show that the CFD modelling can provide results in good agreement with the experiment.