Flow measurements through pipelines and open channels are very important for the management of water resources effectively. Orifice meter is a very common and widely used flow measuring device in pipes as it is very cheap and simple compared with other devices, however, there are many parameters that affect its performance. Also, the orifice is used as an energy dissipation method in water hammer protection devices and hydroelectric power tunnels. Although traditional circular orifice meters have been extensively studied, many points need to be studied. So, experimental research is carried out to study the effect of orifice geometry on energy loss. The experimental tests are carried out using four different types of orifice plates: circular, square, triangular, and hexagonal, the cross-sectional area is changed four times for each one. The flow rate is changed ten times for each orifice ranging from 13.8 to 49.2 m3/hr. Due to head losses occurring at the orifice. General equations are developed for the coefficient of discharge and head loss through orifices based on dimensional analysis. The experimental results conclude that the triangular shapes are better than the other orifice shapes in terms of performance, with reduced head loss and a larger discharge coefficient. By using computational fluid dynamics techniques, the flow behavior through the orifice is analyzed by ANSYS Fluent software. The numerical results confirmed the experimental ones where the pressure head loss for the triangular orifice is the lowest compared with the other orifice shapes.