Wind Tunnel Experiments on Cooling Tower Plumes. Part 2: In Nonuniform Cross Flow of Boundary Layer Type

摘要

Plumes issuing into a boundary layer were studied. The large eddies of the oncoming boundary layer are responsible for sudden changes in plume direction. The type of eddy structure depends on the velocity ratio at that moment. Mean velocities and normal velocity gradients are smaller than in the case of uniform crossflow and the measured turbulence intensities are lower too. The cross-stream turbulence brings high momentum fluid into the wake region and the velocity defect decays very rapidly. Plume dilution is faster in the presence of external turbulence than with uniform cross-flow. The spreading rate is increased dramatically by the external turbulence which causes different effects on the hydrodynamic and thermal fields.