Evaluation of clamp-on ultrasonic liquid flowmeters
Abstract
The clamp-on ultrasonic flowmeter measures the fluid flow velocity and flowrate with the help of ultrasonic waves. Flow profile distortion due to pipe network disturbances cause uncertainty in the flowrate measurement. A numerical and experimental investigation is conducted to model the performance of a clamp-on ultrasonic flowmeter onto a straight pipe and at x/d=1 downstream of a 900 elbow for the flowrate range of 0.3-2.5m3/hr. The average percentage error in the flowrate at x/d=1 downstream of the elbow estimated from the numerical and experimental study is 8.6% and 10.8% respectively. The correction factors suggested for the numerical and experimental data reduces the average percentage error to 0.7% and 2.3% respectively. The repeatability tests show ±1.8% uncertainty in the flowrate. Integrating velocity along the acoustic path can roughly estimate measurement uncertainty due to flow profile without simulating the ultrasonic wave propagation numerically. This research will help increase the use of clamp-on ultrasonic flowmeters in practical applications with reduced uncertainty.