DISCHARGE CHARACTERISTICS OF SIDE ORIFICES IN OPEN CHANNELS

Abstract

A side orifice is a flow diversion structure provided in one or both side walls of a channel to spill/divert water from the main channel. It is widely used in irrigation and environmental engineering. Analytical and experimental studies related to the discharge characteristics of sharp-crested circular side orifices and square side orifices in open channels have been presented in the present study. Considering the side orifice, as large, discharge equations for both the side orifices are derived analytically. Experiments were performed to estimate the coefficient of discharge which depends on the approach flow Froude number and ratio of the diameter of orifice and bed width of the channel. Relationships for the coefficient of discharge, considering the orifice as large and small were developed. It is observed that circular side orifice is more efficient than rectangular side orifice in terms of discharge characteristics when B/L is greater than 0.2. Jet angles and flow pattern in the main channel are observed in the present study.