A concept of mixing ratio of piston air is developed to evaluate the portion of the injecting air from tunnel mixed with the air in platform space of metro system. And a 3- dimensional turbulent model is used to simulate the airflow in metro platform resulted by the ventilation system and moving trains. Field measurement has been conducted to verify the 3-dimensional model. This experiment is performed during the normal operation time of a metro station with constant tracer-gas injection method. The results agree well with the numerical solution.
Modelling techniques were used to verify the success of a "minimal duct" ventilation system proposed for an underground carpark in a prestigious project in Singapore. The procedure to determine the various model scaling parameters, to select the appropriate fans to model the supply and exhaust fans, as well as the "dilution fans"; and to simulate the movement of air through the vehicle access ramps are presented. Measurements from the model were found to be reasonable when compared with results from numerical simulation. However, certain modifications were needed to improve the system.
In the urban environment, there is strong evidence that fine particulates associated with vehicular emissions are linked with respiratory problems and an increase in mortality. The population sector most at risk is the elderly who spend much of their time indoors; consequently, the infiltration of these particles and their subsequent behaviour indoors is of primary concern.
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