Wind Tunnel Study of Gas Dispersion Near a Cubical Model Building.

摘要

The dispersion of effluent plumes emitted from the surface of a cubical model building into its near wake region (less than five building heights downwind) has been examined. The model study was performed in a wind tunnel with a simulated neutrally stratified shear layer. Mean concentration measurements were made on the building surface and within the near wake region of the model building. Measurements of the concentration fluctuation intensity and the peak-to-mean concentration ratio were also conducted in the near wake. The concentration level on the lee face of the model building is greatly reduced by the presence of a nearby sharp building edge. The optimum location for an intake vent on the building, for equal effluent exhaust to vent intake distances, is a position not directly downwind and at a location where the intake cannot 'see' the exhaust vent. The log-normal concentration probability model was found appropriate for measurements in the building wake between one and five building heights downwind. The concentration fluctuation intensity was found to be reduced by the presence of the model building from that of a plume released in an obstructed flow. A simple algorithm, based on the relation of the peak-to-mean concentration ratio and the local concentration fluctuation intensity, suggests an upper limit for the peak-to-mean concentration ratios near the ground centerline.