Document Type : Original Article

Authors

1 MSc Student of Water Structure, Water Engineering Department, Sari Agricultural Sciences and Natural Resources University

2 Associate Professor, Water Engineering Department, Sari Agricultural Science And Natural Resources University

Abstract

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.

Keywords

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