Flow Characteristics at Drops

Abstract

This technical note is an experimental contribution to the study of the supercritical flow at drops. The experimental setup is arranged to measure flow characteristics, which include velocity profiles and several lengths. Because of the similarity of the supercritical flow to the subcritical flow, a basis for the analysis of data is also established. It is found that for a specific discharge increasing the Froude number decreases the relative energy loss, the downstream depth, and the pool depth. For any given value of the Froude number, with increasing discharge the energy loss decreases, but the downstream depth and the pool depth increase. The predictions of flow parameters differ from the measured ones, probably due to the assumptions made in the proposed method, which neglect the entrainment of air at the downstream section and the bed shear stress. An empirical equation is derived to estimate the relative energy loss for supercritical flow. Since the proposed method can be run for any Froude number, it can also be used to predict flow parameters of the subcritical flow with good accuracy.