Experimental study of the accuracy of integrated monitoring and control gate and the water flow in front of the gate

【Objective】 This paper is to investigate how changes in flow pattern at the water inlet influence the measurement accuracy of box-type integrated measurement and control gates and water flow in front of the gate. 【Method】 Using a commonly used 600 mm × 600 mm flow measurement box in irrigation systems as the test subject, 98 model tests were conducted at an indoor testing facility. Disturbance facilities were set up to study the effects of flow symmetry, gate opening, and water level changes on the flow pattern and measurement accuracy in front of the gate. 【Result】 ① The intensity, frequency, and duration of vortices in the flow measurement box vary across different operating conditions. When the measurement box is non-submerged, surface depression vortices are predominant, with minimal impact on measurement accuracy. When the box is submerged and water depth exceeds 20 cm, vortex intensity decreases with increased submergence, but when the depth is less than 20 cm, vortex intensity reaches a maximum, and through-vortices form, causing a significant increase in measurement error. ② The symmetry of the inlet flow pattern is a primary factor influencing vortex formation. Under asymmetric inlet flow conditions, suction vortices are likely to occur in the measurement box, significantly increasing measurement error, with a maximum error of about 22.58%. 【Conclusion】 Adjusting submergence depth, gate opening, and inlet flow symmetry effectively reduces vortex intensity around the measurement box and improves measurement accuracy.