Effect of surface roughness on neutral and dense gas dispersion in the BLWT

Abstract

Measurements of neutral and dense gas dispersion in a boundary layer wind tunnel with different surface roughness were performed. Neutral or dense gas was emitted from a small “quasi-point” source located in the wind tunnel floor. This “quasi-point” source represents leakages of gases from small industrial plants in the urban area. The tunnel surface was either covered with uniform roughness or with a smooth surface in order to create a significant difference in the boundary layer mean velocity profile and turbulence intensity. Also influence of plume momentum on vertical and horizontal distribution of tracer gas concentration above the source was studied. Both neutral and dense gases were marked with tracer gas (ethane) and concentrations were measured with a comb probe connected to four flame ionization detectors (FID). Results have shown that plume momentum significantly affects plume shape. Boundary layer turbulence intensity also affected plume behavior, but to a lesser degree than plume momentum.