Experimental study of turbulent swirling flows

The structure of turbulent coaxial swirling flows is studied in the present work to arrive at a better understanding of the flows with their characteristic recirculation zones and oscillatory behavior, and to provide an experimental data-base for development and evaluation of numerical models of turbulent swirling flows. Extensive flow field mapping of two confined coaxial jets under co-swirl and counter-swirl conditions are carried out. In one set of experiments, mean flow results are obtained with a directional pitot probe to determine the effect of outer swirl on the recirculation zone. As the outer swirl magnitude is first decreased from maximum counter-swirl and then increased to give co-swirl conditions, the size and the reverse flow velocity in the recirculation zone diminishes. In the second set of experiments, for a co-swirl and a counter-swirl condition, detailed maps of mean and fluctuation flow fields are obtained with pitot probe and hot-wire anemometry.