Experimental investigating effect of Froude number on hydraulic parameters of vertical drop with supercritical flow upstream

The supercritical flow as the inflow at upstream of the vertical drops can produce a considerable impact, destruction and erosion at the downstream of drops influence by fall and collision. Therefore in this study, with the aim of evaluation and prediction of the general behavior of hydraulic parameters in vertical drops with the supercritical flow at upstream, 55 experiments were carried out with various discharges and Froude numbers. The experimental results indicated that in the supercritical flows, by increasing the relative critical depth and Froude numbers, the relative length of drop, the relative length of splashing and the relative total length of the drop were increased. However, by increasing the relative critical depth and Froude number, the relative depth of the pool initially increases and then decreases, and the relative energy loss is initially reduced and then increased. By increasing the Froude number at a constant relative critical depth, the relative length of the drop, the relative length of splashing, the relative total length of drop and the relative energy loss increases, and relative depth of the pool decreases. Also, in a constant Froude number, by increasing the relative critical depth, the relative length of drop, the relative length of splashing, the relative total length of the drop and relative depth of the pool increase, and the relative energy loss decreases. The results of the present study with the larger range of Froude number were compared with the previous studies and were studied the reasons for the agreement or disagreement.