Investigation of the effect of counter clockwise submerged vanes on reduced scour around single bridge pier in the sharp bend

In this paper, the effect of counterclockwise submerged vanes on the scouring around the single pier of bridge has been investigated. The experiments were performed on a U-shaped flume with a cylindrical bridge pier. Rectangular vanes were made of Plexiglass. The length and thickness of vanes were used 1.5 and 0.2 times the pier diameter and 75 percent submergence respectively. All experiments were carried out in clear water , discharge 70 l/s and medium sediment size of 1.5 mm. The results indicated that use of counterclockwise submerged vanes, decreased scour hole volume and scour depth around bridge pier. The percentage of scour volume reduction around the piers in the case of counterclockwise submerged vanes are used was approximately 25-40 %. For example, in the experiment of vanes installation with a distance of 5 times the pier diameter from the pier center and distance of 1.5 times the pier diameter of the lateral side, the depth of scour and the volume of scour hole were decreased 8.8 % and 38 % respectively.