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

Downfall flows from different outlet hydraulic structures such as culverts and jets throwing to the 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 studied in this paper. Water jet was modeled using a plastic pipe with a circular section throwing on a Silica bed material with a uniform grading in three different culvert angles of 80, 90 and 100 degrees relative to the vertical axis. The results showed that by increasing the jet angle from 80 to 100 degrees, depth of the scour hole increased and the place where the maximum scour hole depth occurs changed. Besides, by using the Non-dimensional Analysis, a relationship for measuring the maximum depth of the scour hole and maximum height of the scour mound was presented in this paper.