Experimental study of sediment laden flow in a hydraulic jump

摘要

An experimental investigation was made to study the effects of bedload transport on super critical flow and hydraulic jump in a rectangular channel. Experiments were performed in a stilling basin of rectangular cross-section 500 mm wide and 3 m long. Uniform sands of 1.435, 4.05, and 5.555 mm and non-uniform sand of 0.63 mm with different concentration were used in the experiments for various types of hydraulic jump with Froude number ranging from 3 to 9. The results indicate that the sediment size and sediment concentration makes no changes to the incoming super critical flow conditions and therefore, has no effect on the characteristics of the jump (sequent depth, energy loss and length of jump). However, the incoming sediments are deposited in the sub critical zoon (end of jump) and move downstream as bedload. The motion of the sediment is wave-like with a mild slope at the front followed by a raised bed of nearly uniform thickness terminating into a step. This sand wave performs a control section similar to the end sill in a stilling basin and keeps the hydraulic jump position at the beginning of the basin. The thickness and the position of the front of this sand wave are expressed as a function of upstream Froude number.