STRUCTURE OF ROUND, FULLY-DEVELOPED, BUOYANT TURBULENT PLUMES

An experimental study of the structure of round buoyant turbulent plum es was carried out, emphasizing conditions in the fully developed (sel f-preserving) portion of the flow. Plume conditions were simulated usi ng dense gas sources (carbon dioxide and sulfur hexafluoride) in a sti ll air environment. Mean and fluctuating mixture fraction properties w ere measured using single-and two-point laser-induced iodine fluoresce nce. The present measurements extended farther from the source (up to 151 source diameters) than most earlier measurements (up to 62 source diameters) and indicated that self-preserving turbulent plumes are nar rower, with larger mean and fluctuating mixture fractions (when approp riately scaled) near the axis, than previously thought. Other mixture fraction measurements reported include probability density functions, temporal power spectra, radial spatial correlations and temporal and s patial integral scales.