Title: ULTRASONIC WATER MEASUREMENT IN IRRIGATION PIPELINES WITH DISTURBED FLOW
Abstract: Ultrasonic flow meter accuracy was investigated over a range of flow conditions (3 pipe materials, 2 pipe sizes,4 Reynolds numbers, 7 flowdisturbing devices) commonly found in irrigation systems. Flow rate measurements were takenat five locations downstream from a flow disturbance. The measurement accuracy was within 5% of actual flow at a minimumof 10 pipe diameters downstream from the flow disturbances. Errors as high as 36.5% occurred when measurements weretaken close to some flow disturbances. A multiplier was developed to correct for directional bias for devices that fell into theGroup 1 category (single elbow, two elbows, check valve, and 50% open butterfly valve with vertical and horizontalorientation). Applying the multiplier at 4.5 pipe diameters and higher resulted in accuracies within 4% of actual flow. Theregression analysis performed on Group 1 devices showed that the USFM performance was not significantly different for thethree pipe materials, two pipe diameters, and four flow rates.