Investigation and Evaluation of The Effects of Jet on The Pressure Flushing in Hydropower Reservoirs

Pressure flushing is one of the methods in removing sediments from reservoirs. In this method, the sediment around the bottom outlet is scoured locally and it would be necessary to decrease the depth of reservoir water level as much as possible. In this research, for the first time, jet has been used to increase the sediment scour and the sediments removal nearby the dam. To study the effects of jet on increasing the sediment scour, a physical model was developed. Five jets with three different velocities and three nozzle diameters were used in two removal levels of outlet. The results have shown that among the variable parameters, the jet velocity had the most effect on sediment scour. Moreover, the effects of the mentioned parameters on sediment removal output were studied and an exponential dimensionless relationship with high scouring efficiency was found between the sediment removal output and the effective parameters. The tests have shown that jet method has had significant effects on increasing the amount of sediment scour output and can be considered as an alternative method for sediment removal in reservoir management methods.