عنوان مقاله [English]
Compound sharp crested weir for measuring the discharge with reasonable sensitivity and accuracy in a wide range of flow, as appropriate solution can be used. Also the transitional water containing sediment and floating will cause problems in how they function. One of the options that can be used to extend weir-gate combined compound sharp crested weir with gate. The purposed of this research, investigation of combined flow in sharp crested weir in the state of compound weir with circular- trapezoidal- rectangular sections by combining gate with opening height of 1.5, 3 and 4.5cm. Experiments carried out in an experimental rectangular canal with length of 12 meters and width of 5 meters. Based on experimental data the results show that, discharge coefficient in compound weir is in the range of 0.58 to 0.85 and in compound weir- gate is in the range of 0.38 to 0.78. The results showed that for a known head over the weir, the discharge coefficient in compound weir-gate is reduced with increasing the height of the gate.The mean values of the coefficient of determination (R2) and the normalized root mean square error (NRMSE) are 0.96 and 0.06, respectively. The results showed that the use of a linear combination of flow equations in compound weir with circular- trapezoidal- rectangular sections and compound weir-gate, with acceptable accuracy is able to estimate the discharge coefficient.
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