Head Loss Estimation of Water Jets from Flip Bucket of Cakmak-1 Diversion Weir and HEPP

A jet issued from flip bucket of spillway of a dam interacts with the surrounding air and develops into an aerated turbulent jet. Depending on the relative jet thickness, the fall height and the level of turbulence, the jet may be dispersed in air forming an aerated water body which will eventually plunge into the river surface at sufficiently far downstream of the flip bucket. If not aerated, the jet may have a larger impact on the river bed causing excessive scouring of the river bed. Dispersion of jet by aeration is the practical tool to reduce the jet impact. The spillway of Cakmak I Diversion Weir and HEPP project located in Kahramanmaras province of Turkey is used as a case study to estimate trajectory lengths with air entrainment. Depending on projectile motion theory, head losses due to the air entrainment can be determined between the difference of the trajectory lengths with and without air resistance. Empirical equations were used to calculate the jet trajectory length with and without air entrainment. For the same conditions, the flow is modelled with commercially available computer software that uses volume of fluid (VOF) technique. Results from empirical equations and from numerical simulations are compared and differences between the results are discussed.