Deflector Effect on Chute Flow

Jet deflection and energy dissipation of ski jumps guarantee the safety of hydraulic structures. Deflectors on spillways and bottom outlets are mostly complex constructions. The aim of this study is to find simple-shaped deflectors allowing for jet deflection into the tailwater, thereby characterizing the parameters of the trajectory under different approach flow conditions. The test program included eight right-angled tetrahedrons and two vertical plate deflectors. A systematic variation of the approach flow depth and Froude number, in combination with different deflector alignments, resulted in basic principles for deflector design. To study scale effects caused by viscosity and surface tension, three symmetric deflectors were tested as a model family at different approach flow depths. The results indicate the importance of the approach flow Froude number and the relative deflector height on the jet trajectory. The relevant jet parameters, including the deflection angle, the maximum jet elevation, and the jet impact onto the tailwater channel, are specified.