Flow through Elbow as a Measurement Device for Surface Irrigation

A convenient water measurement and other control techniques in sustainable irrigated lands are important to support the management of fields. An experimental study is carried out to study free flow though standard elbow bend fixed on a plate as a device. The effect of diameter, the height of opening, and the contraction ratio for different flow head-discharge on sixteen models were investigated. It was found that the flow approaching the inlet behaves as a weir flow phenomena, when the ratio of the head to the diameter is less than ½, and the flow is an orifice flow phenomena when the ratio exceeds ½. The discharge coefficient (Cd) Varies between 0.51 and 0.84 for the weir flow and has the value between 0.35 and 0.42 for orifice flow. The equation combining the dimensionless parameters had been found by the regression of the experimental data for the weir flow.