Application of Ultrasonic Flowmeter in Yellow-river Irrigation Channels

Abstract

【Objective】 As the allocation of Yellow River water for irrigation diminishes, there is a pressing need to improve irrigation management. A fundamental requirement for achieving this objective is a comprehensive understanding of water flow in each irrigation channel. The aim of this paper is to propose a method to improve the precision of ultrasonic flowmeters for measuring flow rates in these sediment-laden channels. 【Method】 The proposed method is based on the principles of multi-channel ultrasonic flow measurement. It entails a comprehensive redesign of the integrated measurement and control gate. An automatic gate is installed to regulate flow through the gate, while a multi-channel ultrasonic measuring tank and an ultrasonic level meter are placed downstream of the canal gate to measure canal flow. The angle of the ultrasonic transducer on the measuring tank is adjusted by shifting from the original 45° to 60°. This adjustment shortens the effective distance of ultrasonic sound intensity, reducing the attenuation of sound intensity caused by factors like sediment, bubbles, and suspended impurities in the water. An additional ultrasonic level gauge is integrated into the upper section of the measuring tank, and channel flow is measured through the coordinated operation of the ultrasonic level gauge and ultrasonic transducer. 【Result】 The separate installation of the control gate and the flow measuring tank has no adverse impact on gate automatic control or the monitoring and analytical calculation of flow measurement data. Furthermore, it stabilizes water flow within the canal and decreases the Reynolds coefficient of the channel flow, reducing interference from culverts and water flow noise on sound intensity. In cases of high sediment concentration, the shortened effective distance of the channel ultrasonic sound intensity leads to reduced sound intensity attenuation. This enhances the ultrasonic transducer's ability to recognize sound intensity and substantially improves flow measurement accuracy, especially in conditions characterized by high sediment content and impurities. The separate reconstruction of the gate and measuring flume at the 303 bucket mouth of the three trunk lines was compared under varying water depths and sediment concentrations. The measurement error in several scenarios remained within 5%. 【Conclusion】 The automatic water measurement facilities developed in this paper meet the rigorous requirements for automatic flow measurement and control in irrigation areas. The results have potential for application in modernization of sediment-laden channel water measurement in high sediment concentration areas, thus contributing to the information technology advancements in such channels.

Keywords

• ultrasonic flowmeter
• flow measurement
• yellow river channel
• high sediment flow
• measurement