Influencia de la geometría de entrada en tomas sumergidas sobre la sumersión crítica para la formación de vórtices que arrastran aire

An experimental study was conducted to study the influence of the geometry of a horizontal submerged intake on the formation of air-trapping free surface vortices. Two types of inlet profiles were tested, bellmouth and sharp edge. In both cases the inlet is inserted into the forebay. Flow rates varied between 6 and 21 l/s and submergence varied between 4 cm and 40 cm. In a dimensionless graph, where the relative submergence, S/D, was expressed as a function of the Froude number, regions where no air-entraining vortices form where delineated for each case. Vortex type was determined for each point and the regions where no vortex is formed were delineated. It was found that as the Froude number increases, a greater relative submergence is needed to avoid air intrusion. In addition, the sharp edge intake requires a greater relative submergence than the bellmouth intake in the range of Froude number tested to avoid the formation of air trapping vortices. Behavior of type B vortices was also studied. It was found that periods of air capture were longer when a sharp edge inlet was installed for the same hydraulic conditions than for the bellmouth inlet.