Discharge characteristics of lateral circular intakes in open channel flow

• Flow characteristics of lateral intake with and without bellmouth opening are studied.
• It depends on approach flow Froude number and ratio of width of orifice and channel bed width.
• Regression equations for Cd of lateral intake for above conditions are proposed.
• The discharging capacity of the intake with bellmouth opening is higher than the other.

Intakes are widely used for flow diversion and its control in the open channels. Circular intakes with bellmouth transitions are used to enhance the discharging capacity of the intakes. Analytical and experimental studies for flow through lateral circular intakes with and without bellmouth in open channels are presented in this paper. This study indicates that the coefficient of discharge for the lateral intake under uniform flow is dependent on the Froude number of the approach flow in the main channel and the ratio of width of the orifice to the width of the main channel. Collected data in this study are used to develop regression equation for the coefficient of discharge. The computed discharges using the proposed equations in this study are within ±10% and ±7% of the observed ones for intake with and without bellmouth, respectively. The discharging capacity of an intake with bellmouth is higher than the intake without transition. Sensitivity analysis indicates that the discharge through bellmouth intake is more sensitive to the low head, as the head increases, the sensitivity for a particular size of intake decreases.