Effect of same phase hydraulic jet on reduction of scour in 180-degree bend

The present study has investigated the effectiveness of same phase hydraulic jet on reducing scour at river bends. In this method, a perforated tube was placed along the bend on the bed, and water was injected into the bend flow from both ends of the tube. This study mainly intends to make a water screen against the secondary flows at river bends to prevent them from reaching the outer bank. Results showed that the place of the maximum scour depth moved from around the outer bank of the bend in the control experiments towards the middle parts of the section in the main experiments. Besides, with the increase in the spacing of the tube ports, the maximum scour depth decreased. Also, the maximum scour depth was reduced by decreasing the distance between the perforated tube and the outer wall of the bend. On the other hand, the results showed that the maximum scour depths at 90, 130 and 175 degree sections of the bend was respectively reduced by 60, 64 and 87 percent.