Experimental Investigation of the Anti-Vortex Devices of Beyhan 1 Dam and Hydroelectric Power Plant Water Intake Structure

Abstract

Hydraulic model tests of the intake structure of Beyhan 1 Dam having four units were carried out at Hydromechanics Laboratory of Middle East Technical University, Ankara. In order to investigate the flow pattern, and formation, development and dissipation of vortices at the intake structure under different operation conditions of the units, and to determine the types of anti-vortex devices to avoid the air-entraining vortices, a model of 1/29.43 length scale was constructed. The model area covers an about 200 m × 300 m section of the Beyhan 1 reservoir, the intake structure having four units, the trash racks and penstocks.Experiments were carried out at various reservoir water levels with specified unit operation discharges for various unit operation conditions. From the observations and experimental results, it was concluded that air-entraining vortices were forming at the intakes when the reservoir water level was minimum, RWL=977.0 m. Flow separation zones were forming; along the inner lengths of the side walls surrounding the intake structure and behind the trashrack piers at any RWL tested. In order to reduce the strengths of the vortices forming and to prevent the intakes from air-entraining vortices, in the first phase of the experimental study, several anti-vortex devices; continuous plates constructed on top of the intakes, continuous projected head walls and continuous projected head walls with vertical unit-separation walls were tested under various flow and unit operation conditions to find the anti-vortex device that gave the best performance. It was also stated that the arrangements to be made on the geometries of the side walls and trashrack piers, if possible, will improve the flow conditions at the intakes.