Abstract
Time-lapse photography was used to estimate the speed of vortices in condensed plumes from a bank of mechanical draft cooling towers and a hyperbolic natural draft cooling tower. At a distance of about 30 m downwind from the towers, the median tangential velocity of the vortices at the edge of the plume is about 2 m s−1 in the downward direction, for ambient wind speeds of 7 to 13 m s−1. The standard deviation of turbulent fluctuations of tangential speeds of the vortices is about 1.8 m s−1 for both types of towers.
