Observations of confined spray-driven air vortices

A series of experiments was conducted in a right circular cylinder to determine the flow pattern that develops when air circulates from the drag induced by falling water sprays. Two different flow patterns were visually observed and recorded by the distribution of spray mass flux. In one pattern, the airflow took the form of a single three-dimensional toroidal vortex with the air flowing up the sides of the container and down the center thereby concentrating the water sprays in the center of the container. The toroidal vortex was an unstable flow pattern unless the water spray was uniformly distributed along the ceiling. The second pattern was stable and took the form of a single nearly two-dimensional stationary roll with the air flowing up one side of the container and down the other thereby concentrating the water sprays along the downflow side. As the water pressure in the nozzles was increased, the roll did not remain stationary but rotated slowly about the central vertical axis of the container.