Dense gas field experiments with obstacles

A recent dense gas dispersion project is presented, with emphasis on the field experiments. During these experiments we have studied the effect of obstacles on continuous releases of liquefied propane. A solid wall perpendicular to the wind direction was observed to have a general diluting effect on the dense gas cloud, but at some positions above ground level the concentration was intensified in the presence of the obstacle as a result of increased cloud height. Propane concentrations can be derived from sonic anemometer measurements using a new technique, and the paper has a brief discussion of turbulence inside the gas cloud, including gas flux and concentration fluctuations. Two gas sources were used - a nozzle and a cyclone producing releases with and without initial momentum. The jet from the nozzle was found to have an important effect on the dispersion, producing a lot of turbulence and increasing the vertical gas flux.