In the present study, sill with orifice were utilized to enhance energy dissipation downstream of these structures. For this purpose, a sill with the same width as the channel, a fixed height, and 1, 2, 3, and 4 perforations with a constant diameter of 2 centimeters were experimentally investigated. The results indicated that under the presence of the sill, the specific energy and Froude number downstream of the gate decreased by more than 13% on average across all models. The introduction of sill and the increase in their number in the orifice led to increased turbulence in the flow, resulting in a reduction of specific energy downstream of the gate. A quantitative comparison of the results obtained from the specific energy downstream of the gate shows that the gate with orifice sills, with 1, 2, 3, and 4 orifices, reduces the specific energy downstream of the gate by an average of 29%, 32%, 40%, and 48%, respectively, compared to the non-orifice sill. Additionally, the non-orifice sill reduces the specific energy downstream of the gate by 14% compared to the non-sill condition. Furthermore, the analysis of depth ratios and energy dissipation in hydraulic jumps revealed that the sill with 4 orifices sill the lowest depth ratio of the jump, while a decrease in the number of orifices increased the contribution of hydraulic jump to the energy dissipation of the flow.
