Generation and Sampling of Helium Clouds for Studying Mass Diffusion

Abstract

An experimental technique to study diffusion of helium gas from an instantaneous point source within a neutral turbulent boundary layer is described. Concentrations from a simulated point source, located at a fixed height above a smooth surface, are measured for various downstream cross sections of the diffusing plume. Statistical parameters are used to present the concentration data in terms of the time-averaged as well as the maximum instantaneous concentration at a point. The results of the analysis are compared with those of other investigations.