Date of Award:

12-2011

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Steven L. Barfuss

Committee

Steven L. Barfuss

Committee

Michael C. Johnson

Committee

Robert E. Spall

Abstract

In the arid west, water is among the most valuable of resources. One of the most critical aspects of water resource management is that of flow measurement. Accurate flow measurement data is needed to effectively manage any water distribution system, whether for culinary or irrigation use. In order to successfully and accurately measure water flow in pipes, it is recommended that a straight section of pipe be installed immediately upstream from the flow meter to avoid distorted flow patterns at the metering location. In many existing piping scenarios, however, such flow conditions are impossible to achieve.

The performance of ultrasonic flow meters in non-ideal piping scenarios was studied using laboratory experiments and numerical computer models. The ultrasonic flow meter was installed downstream of a single 90-degeree elbow and the error in flow measurement downstream of the elbow was recorded. The ultrasonic flow meter measurement errors downstream of the elbow were always negative, with errors as great as -16%. This indicates that the ultrasonic flow meter under predicts the actual flow rate in a pipe when used in non-straight piping. In general, the ultrasonic flow meter performed less accurately closer to the elbow due to the distorted flow patterns created by the elbow.

Using the same physical conditions, numerical computer models were built that utilized Computational Fluid Dynamics for turbulent flows. Using the results from the numerical models, a correction curve was applied to the laboratory ultrasonic flow measurements. By applying the correction equation, the measurement error was reduced by nearly 90%. Computational Fluid Dynamics appears to be a viable tool for studying flow disturbances and making corrections to flow measurements. It is anticipated that this approach may prove valuable for other non-ideal piping scenarios. This will result in more accurate flow measurement and better management of valuable water resources.

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Comments

This work made publicly available electronically on November 21, 2011.

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