Experimental Assessment of Discharge Coefficient of Curved Compound Weir-Gate

Compound weirs, as an appropriate solution, can be used for measuring flow discharges with reasonable sensitivity and accuracy in a wide range of flows. However, sediment laden flows will cause problems in their functions. This problem can be coped with trough combining gates and compound weirs. In this research, based on dimensionless parameters obtained from dimensional analysis and using a smart and new method named Gene-Expression Programming (GEP), an equation has been proposed for prediction of discharge coefficient in compound curved weir-gate structures. The aim of this research is investigation of hydraulic characteristics of compound curved weir-gate as well as providing a relationship for prediction of discharge coefficient of these structures, based on the hydraulic and geometric parameters.

The experiments were done in a rectangular flume by 9 meter of length and 0.4 meter of width. Then, the obtained data were used to estimate the discharge coefficient. This study has been assessed by using of variations of flow discharge, gate opening, weir opening and angle of curve as parameters of experimental channel. Also, the effects of hydraulic of flow and the geometry of duct were considered in the discharge coefficient estimation. After these, Gene Expression Programming (GEP) was used to set an equation to determine the discharge coefficient with a high accuracy.

The discharge coefficient were calculated by analyzing the obtained experimental data. Next, an equation was determined by method of dimensional analysis and gene expression programming tools to estimate the discharge coefficient by correlation coefficient (R2) of 0.992 and 0.662 for training and testing data, respectively. Furthermore, the findings showed that the most discharge coefficient occurred in the experiment by a_1/b_1 =4/15, where a1 and b1 denoted on gate height and gate length, respectively. Also, increasing trend in discharge coefficient was seen by increasing the Froude number and h/P .

The results show that (GEP) intelligence approach is an adequate model to predict assessment of discharge coefficient of curved compound weir-gate. Also, the results of traditional regression equations were improved using this method. In the other words, the results implied on the ability of the gene expression programming (GEP) to assess the discharge coefficient of this structure compared with regression method. Also, according to the results, the geometric parameters have the main effect on the discharge coefficient of curved compound weir-gate. So, use of the gene expression programming (GEP) is suggested in future studies related to this topic.