Experimental development of wall-bounded turbulent jets as related to tunnel blast into a subway station

Passenger comfort and safety on the platform is affected by outdraft of tunnel air ahead of the train. These drafts reach speeds of 10 m/s. Blast tubes in the urban environment are costly while a safety interlocked system of doors to mechanically shield the platform present operational problems. This research has developed a rational aerodynamic model to predict platform blast and the effect of architectural geometry on them. The analytical code have been supported and validated by measurements on physical models.; The first component of the model has been developed in a computer code describing the time/velocity schedule of the incompressible tunnel blast as a function of the tunnel/train parameters.; A 1% scale model of a station and train with variable parameter (train speed, tunnel blockage ratio, station geometry) has been used in initial and detailed testing, using air, to measure the flow. The tunnel exit diameter was 2 inches and exit speeds were 38 and 62 ft/sec (Re = 38,000 and 60,000. Typical Re for full scale stations is 4 million.). Flow measurements were used to examine phenomenon peculiar to this flow situation and to determine physical constants. The physical constants describe flow within a station as a function of location and tunnel center line velocity (output from the above time/velocity code) in the final component of the model.; Station cross-sections from 9X9 to 3X3 tunnel radii were tested. Although Re = 30,000 min. the flow was definitely turbulent.; During flow measurement, nearly a forty thousand data points were taken. This raw data was used to develop constants used in a model, using a Gaussian distribution, developed in this paper. The model is valid for station configurations not tested.; A series of vane tests were conducted within the 1% model to visualize the flow within a station and have been correlated with the above reduced model measurements.