A radar flow meter for automatic measurement of open channel flow

LI Yincai; LI Bin; LI Wei; YIN Wenbin; HAN Wei; WU Xiaolei

doi:10.13522/j.cnki.ggps.2023485

Abstract：[Objective]The radar flow meter utilizes electromagnetic waves to measure water velocity,offering an efficient,non-invasive method for water flow measurement.In this paper,we experimentally investigates its feasibility for automatically measuring the cross-section flow in open channels,in attempts to improve water resource allocation and support intelligent,precision-based water-saving irrigation systems.[Method]The velocity-area method was used in the experiment,where the radar velocimeters were installed at the heights of 2.1 m and 4.7 m above the canal bottom on a rigid truss bridge.The equipment automatically measured surface velocity and midstream depth.A mathematical model was developed to calculate the cross-sectional area and flow rate based on these measurements.The calculated flow rates were compared with those obtained from an electromagnetic flowmeter installed in a 600 m outlet pipe,upstream of the section.[Result]Comparison between flow rates measured by the radar flow meter and the electromagnetic flowmeter showed that the flow rate error ranged from 0.014 to 0.026,meeting the requirements for water flow measurement.For the radar velocimeter installed at heights of 2.1 m and 4.7 m over the bottom,their system errors were 0.89%and-0.79%,with the associated random uncertainties being 2.22%and 2.88%,respectively.For full-section precast concrete slab masonry,the measured flow rate error was 0.02.The overall accuracy of the flow measurement system exceeded 95%.[Conclusion]Radar velocity measurement technology satisfies the requirements for open channel flow in in irrigation districts.The developed model can accurately calculate average flow velocity,enables automatic,accurate flow measurements in large open channels.The system is well-suited for precise flow monitoring and management in modern irrigation systems.