Curved spillway with ceiling flow

1. When designing hydrostations having a concrete dam it is expedient under certain conditions to use deep free-flow spillways with flow along a curved ceiling as the permanent spillways. In a hydraulic respect they have substantial advantages over the usual types of deep spillways. The considerable aeration of the flow permits eliminating the lining of the spillway bottom and lessens the danger of the occurrence of cavitation on lower-lying parts of the spillway passage. 2. The main feature when designing such a type of spillway is the selection of the area of the outlet section, the size of which in many respects determines the character of the flow regime.