Experimental Investigation of Bed Variations due to Circular Culvert Jet with Different Angles

Downfall flows from different outlet hydraulic structures such as culverts and jetsthrowingtothe erodible downstream bed cause scour hole and changes in the downstream bed topography. Therefore,by performing some physical modeling tests on culvert jet flow under different angles, changes in the downstream bed topography under the effect of different parameters such as flow rate, depth of the tail water and the important factor of falling jet angle of the culvert were studiedin this paper.Water jet was modeledusing a plastic pipe with a circular section throwing on a Silica bed material with a uniform grading in three different culvert angles of80, 90 and 100 degreesrelative to the vertical axis. The results showed that by increasing thejet angle from 80 to 100 degrees,depth of the scour hole increasedand the place where the maximum scour holedepth occurs changed. Besides, by usingthe Non-dimensional Analysis, a relationship for measuring the maximum depth ofthe scour hole and maximum height of the scour mound was presented in this paper.