Mass transfer studies were made for an air-carbon dioxide gas system flowing through a 4-inch cylindrical conduit at Reynolds numbers of 1, 500, 5, 000 and 10, 000. It was the purpose of this work to investigate turbulent transport mechanisms in order that basic theory in this area be expanded. The experimental technique consisted of introducing a carbon dioxide tracer into the center of a moving air stream and determining concentration and velocity distributions at various downstream positions. Gas samples were removed by means of a pitot tube and analyzed by a thermal conductivity cell. A circular five-loop hot-wire anemometer was used to establish the velocity profiles.
Roley, George and Fahien, R. W., "Gaseous diffusion at moderate flow rates in circular conduits" (1960). Ames Laboratory Technical Reports. 39.