Author(s)

P. Michálek & D. Zacho

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. Keywords: gas dispersion, quasi-point emission source, surface roughness, BLWT. 1 Introduction Air pollution has become a serious problem in the last few decades. Due to a large amount of industrial chemical plants, which use many dangerous chemical substances, there may occur and sometimes really occurs a leakage of different gases. The modelling of non-buoyant or dense gas dispersion in the air in case of accidents or terrorist attacks is therefore important from the point of view of population protection, because non-buoyant and dense gases disperse near the land surface, thus these gases may threaten human life and health. The process of Test Establishment, Prague, Czech Republic

Keywords

gas dispersion, quasi-point emission source, surface roughness, BLWT.