COMPARING HYDRAULIC JUMP IN OGEE SPILLWAYS WITH DIFFERENT SLOPES

Torrents have been recognized as main factor of destruction of structures and barriers in downstream of spillways of the dams. For this reason, one of the important issues which experts face is prediction of hydraulic jump. Although many studies have been conducted to reduce hydraulic jump and reduce torrent energy, most of them have been discussed for use of optimal spillways and slope of spillways. In this paper, hydraulic jump has been studied after performing laboratory model of the ogee spillways with two different slopes of 28 and 188 degrees. At the end, results of tests were compared in two slopes and it was concluded that length of hydraulic jump for flows of 7 and 9 l/s in slope of 28 degrees for ogee spillways of 60 and 70 cm and hydraulic jump length for the similar flows in slope of 18.8 degrees for ogee spillways of 45 and 65 cm. this has shown considerable reduction of hydraulic jump in slope of 18.8 when compared with slope of 28 degrees.