Stack downwash

Stacks that have a low vertical discharge velocity relative to wind speed at the stack exit suffer from "downwash," which occurs when the plume is sucked downward into the wake behind the stack. High vertical exit velocity will reduce this downwash when it is greater than 1.5 times the wind speed at stack exit. However, there is an energy cost associated with the increase in the exit velocity. An increase in stack height validated with wind modeling could result in energy savings. [Wilson, 1983]


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