Characteristics of flow through orifice-meter

Flow measurements in pipes and open channels are critical for successful water resource management as the economic value of water has increased. Orifice meters are typically used as flow-measuring devices in pipes because they are cheap and simple compared to other devices. Also, orifices are used as energy dissipation methods 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 and numerical research is carried out to study the effect of orifice geometry on energy loss and the discharge coefficient. The experimental tests are carried out using two different types of orifice plates: circular and triangular, for each one the cross-sectional area is changed four times. The orifice is installed on a 10 cm diameter transparent pipe. The flow rate is changed ten times for each orifice ranging from 13.8 to 49.2 m3/hr. A general correlation equation for the coefficient of discharge is deduced. It was found that the triangular orifice shapes are better than the circular 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 lower than the circular orifice and vena contracta is located at a distance equal to half the pipe diameter downstream of the orifice plate.