Measuring Variable Discharge Under Partially Full Pipe Flow

Accurately measuring the discharge in partially full pipe flow is both difficult and demanding. In this regard, a new meter sensor using microwave technology has been evaluated for determining partially full pipe discharge across a range of flow depths. A range of experiments with smooth PVC pipes of two different pipe diameters (101.6 and 152.4 mm) at two different pipe slopes (1° and 2°) were carried out under turbulent (Reynolds numbers = (0.27–3.25) × 105) and supercritical flows with Froude numbers Fr in the range of 1.5 ≤ Fr ≤ 3.6. Our results showed that when combining the microwave sensor readings with either the Chezy equation or Manning’s law, reliable discharge predictions were found compared to the measured discharge across all experiments. The range of R2 values obtained from the plots of predicted versus measured discharge were all greater than 97%, indicating an accuracy allowing the meter to be used in commercial applications.