Calibration and Optimization of an Insertion Electromagnetic Flowmeter with the Aid of Numerical Analysis

Accurate measurement of the volumetric flow rate of working liquids is essential for process control, as well as energy consumption evaluation. Electromagnetic flowmeters have gained popularity in applications where low-pressure drop and low maintenance are required. Dwyer Instruments, Inc. recently developed an adjustable insertion electromagnetic flowmeter (IEF) featuring accurate and reliable measurement. However, unexpected and non-repeatable behavior in the K-factor was observed during the calibration process. The K-factor is the coefficient used to convert the measured electric potential to the flow velocity in pipes, and the non-repeatable behavior imposes challenges for precise measurement. A one-way coupled magnetohydrodynamics model was developed to reduce the effort and time of on-site troubleshooting and optimization. By modeling the measurement process, the transition of flow regimes and the regeneration of the boundary layer on the electrode surface were identified as the causes of the non-repeatable issue. Then, a series of parametric studies were performed to provide reliable solutions. A new design with further embedded electrodes to allow the smooth transition between boundary layers was recommended. The field test showed excellent repeatability by using the new design, and the non-repeatable issue was entirely resolved. The improvement in the IEF design was implemented in production in less than one week, and it reduced the calibration time by 50%.

Flow distortion effect on electromagnetic flowmeter and mitigation using magnetic flux manipulation

The effect of velocity profile distortion on the performance of flow sensors like the electromagnetic flowmeter has been a popular topic in flow measurement research. In many of the investigations computational modeling has been useful as a tool to understand the impact of flow distortion on flowmeter measurement accuracy. However, a more realistic investigation can be conducted by a model with ability to account for three-dimensional variation in fluidic and electromagnetic characteristics. In this research paper, a multiphysics model of the Electromagnetic flowmeter accounting for three-dimensional flow distortion effects and independent of experimental measurements is developed and validated. The model integrates the flow and magnetic fields to yield the induced electrical signal, and is a departure from the popular weight function calculation approach. The model predicts flow distortion effects realistically and is employed in evaluating an idea to mitigate flow distortion problems: manipulating the magnetic field to minimize distortion effects. It is seen that while flow distortion induces a 3 to 4 % error in a flowmeter designed arbitrarily, proper design of the coils can reduce this error to an insignificant level.

Accuracy and Reliability Analysis of Pipe Irrigation Metering Device for Sandy Water Source

Sandy water sources are widely distributed and are important for agricultural development. However, no explicit result has been achieved in the research of the accuracy and reliability of pipeline metering devices as well as flow rate measurement objects (water or water–sand) of different metering devices in the process of pipelines conveying muddy water. In this study, seven kinds of sediment concentration gradients, C0–C6 (0.2–7.19%), and three different flow velocities (1.0 m/s, 1.25 m/s, 1.5 m/s) were set up, and a comparison measuring method was used to compare the flow values of three kinds of metering device (electromagnetic flowmeter, ultrasonic flowmeter and water meter) with a right triangle weir. The accuracy and reliability of the metering device were obtained by analyzing the change law of the relative error between each metering device and the right triangle weir under different flow velocities and different sediment concentrations, and the flow rate measurement objects of each metering device were finally clarified. The relative error between the electromagnetic flowmeter and right triangle weir decreased gradually with the increase in the flow velocity when the sediment concentration was constant. The maximum difference of the relative error between the electromagnetic flowmeter and the right triangle weir was 2.53% when the flow velocity was constant. Additionally, the minimum differences of the relative errors of the ultrasonic flowmeter and water meter were 2.67% and 6.90%, respectively. The measured flow law of the electromagnetic flowmeter was more in line with the measured flow law of the water–sand mixture measured by the right triangle weir. However, the relative errors of water and water–sand measured by the ultrasonic flowmeter and water meter fluctuate greatly, which does not accord with the law of muddy water measured by the right triangle weir. The results showed that the electromagnetic flowmeter has the best reliability among the three metering devices, and the accuracy can be improved by calibration before use or increasing the flow velocity of the pipe network. Under the sand grading used in this study, the electromagnetic flowmeter was recommended to measure the flow rate of pipe irrigation for sandy water sources in this paper.