Flow Pattern Control by Entrainment Regulation

A technique for controlling the flow to a vortex zone trapped between the top of a shallow submerged slot outlet, the free surface, and two lateral wing-walls is examined experimentally to show that it may be used to control the flow pattern near the slot outlet. The range of wing-wall crest elevations for which flow patterns may be controlled is shown to be a function of wing-wall length. The stability of the flow pattern is also examined experimentally and found to depend, for a particular wing-wall spacing, on the submergence of the slot outlet and on a Froude number based on average outlet velocity and wall spacing. The flow pattern control technique may have value in back-fitting some existing outfalls on thermal power plant outlets where strict temperature control is required.