Study on the Effect of Different Operational Parameters on Ultrasonic Cross-Correlation Flowmeter Performance Using CFD Simulation

Among the flow measurement technologies, the ultrasonic cross-correlation flowmeter (UCCF) has received much attention due to its high accuracy, performance independency from sound speed and no pressure drop. In industrial plants, due to space constraints and equipment special arrangement, the flowmeter is not always located at the ideal position. Under these conditions, the calibration factor plays an important role in increasing the accuracy of the flow measurement. The calibration factor is the function of the flow Reynolds number, the straight pipe length at the upstream of the flowmeter and the roughness of the pipe. In present study, with the aid of CFD simulation and using Reynolds Stress Model (RSM), the air flow inside the pipe was simulated in range of Reynolds number from 3.16×104 to 3.16×105. Then, with the aid of UCCF analytical model, the effect of the mentioned parameters including flow Reynolds number, the straight pipe length at the upstream of the flowmeter and the roughness of the pipe, on the performance of the UCCF were investigated. The simulation results show that the changes in shape and curvature of velocity profile inside the pipe has an important role in analyzing and interpretation of the changes in calibration factor. As the flow Reynolds number increases, the velocity profile at the pipe section becomes flatter, so the calibration factor increases. The results also demonstrate that as the flow moves inside the pipe (prior to fully developed length), the curvature of the velocity profile increases firstly and then decreases. In contrast, the calibration factor decreases firstly and then increases. It was also concluded that by changing the pipe material from carbon steel to cast iron and increasing the pipe roughness, the velocity profile becomes more rounded, so the calibration factor decreases.