Hydraulic analysis of parabolic flume for flow measurement

• Hydraulic characteristics of parabolic flumes, long-throated flumes and Parshall flumes are numerical simulated.
• Computational results matched well with laboratory measurements.
• Parabolic flumes installed in the U-shaped channel resulted in merely 35% of water head loss of the long-throated flume or 30% of the Parshall flume when measuring flow.
• New discharge calculation equations applicable to channels of various slopes were obtained.
• Parabolic flumes can serve as accurate devices for flow measurement in open channels.

Parabolic flumes were designed in the 1994 [7] as an efficient way to provide accurate flow measurement in U-shaped channels. Three-dimensional flow fields in parabolic flumes, long-throated flumes, and Parshall flumes are simulated using the volume-of-fluid model. The hydraulic model was validated by using data of physical model testing. The velocity and turbulent kinetic energy dissipation rate in typical sections of the three measuring flumes are analyzed and the total head curves of the three flumes are obtained. The results indicate that the Parshall flume installed in a U-shaped channel leads to a high water head loss, whereas the water head loss for the parabolic flume is only 35% of that of the long-throated flume or 30% of the Parshall flume, which makes parabolic flumes more suitable for U-shaped channels. A formula for calculating discharge that is applicable to channels of various slopes is theoretically derived. Parabolic flumes are demonstrated to be accurate enough to satisfy the demands of water discharge measurement.