Flow through side-combined structure in a channel bend under subcritical flow regime

Abstract

ABSTRACT In this paper, the effects of the nondimensional parameters influencing the discharge coefficient of a side-combined structure located in a channel bend were studied using 288 experimental data. Experiments were conducted in a rectangular recirculating U-shaped channel (0.6 m width and 0.7 m height) for different discharges and depths of flow in the channel. The effects of approach Froude number Fr , the ratio of the gate height to gate opening d/a, the ratio of the approach flow depth to gate opening h 1/a, and angle of the bend curvature α on the discharge coefficient under subcritical flow conditions are investigated. It was found that the flow diversion by a side-combined structure leads to a reverse flow, two separation zones, and a stagnation zone in the main channel. The specific energy remains constant along with the side-combined structure. It was found that the discharge coefficient is a decreasing function of Fr and d/a. Moreover, the discharge coefficient increases by increasing h 1/a. By changing the location of the side-combined structure along the channel bend, the discharge coefficient reduces from upstream, reach to a minimum value at α= 90ᵒ, and increase further downstream. The discharge coefficient of a side-combined structure is maximums when it is located at section 115° of the bend. New equations for the discharge coefficient of a side-combined structure under subcritical flow conditions were obtained.