A Highly Accurate Flow Measurement by Ultrasonic Flow Meter Based Simulation and Experiment
Date Issued
2009
Date
2009
Author(s)
Yang, Fong-Ruey
Abstract
A highly accuracy of flow measurement is very important for many industrial applications. In Taiwan, a turnover of natural gas custody transfer reaches 100 billion NTD per year. If an error goes up to 1% for a flowmeter with no correction, the amount of loss in trade achieves one billion per year. As a result, selection, operation and calibration of a flowmeter is of great importance in trade business.everal advantages of an ultrasonic flowmeter over others are self-diagnosis, no moving parts, simple structure and low maintenance cost. The thesis investigates the flow-field effect on ultrasonic flowmeter, and demonstrates the superior results in accuracy by using numerical and experimental approaches. The ultrasonic flowmeter was experimentally installed downstream in a pipeline with an out-of-plane 150 mm single elbow and thus following along a 400 mm header. Averaged velocity of the flowmeter was integrated over averaged velocities of all paths by applying suitable integration techniques, and then obtained the flow characteristics of the flowmeter. The specific numerical integration method for equal interval was developed based on the Simpsons’ 1/3 rule method in accordance with the configuration of the experimental ultrasonic flowmeter, but Gaussian and Tchebychev methods for unequal interval methods generally. his paper explored successfully the qualitative and quantitative analysis of flow field in pipeline imposed on ultrasonic flowmeter. With the installation of the flow conditioner, the non-symmetry flow and swirl flow of disturbant factors were effectively reduced. Meanwhile, the flow field was nearly stable from a distance of 43.5D. The optimum position of flow meter was located above 10D downstream of flow conditioner. With a typical case of flow conditioner installed 3.5D downstream of the 90° elbow, the flow rate metering deviated was less than 0.36%. The Instromet Q.sonic-3 meter that was placed at 3.5D–43.5D downstream of an elbow showed the error of within 0.0%~-0.8% in a condition with and with no a flow conditioner. These experimental results were in an agreement with the predicted errors of simulation of the flow integration technique for the ultrasonic flowmeter of beyond 4 paths. This indicates the validation of the simulation approach to the experiment practically, and provides a guide of pipelines for further design in modular package.
Subjects
ultrasonic flowmeter
installation effect
computational fluid dynamics
calibration factor
quadrature
Type
thesis
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