Ultrasonic spectroscopy of liquid filled piezoelectric tube
Doctoral Thesis
2006
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University of Cape Town
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Abstract
The characterization and classification of liquids through instrumentation is essential in many industries. As such, measuring the characteristics of liquids is not just useful as a control parameter within an industrial process; such measurements can also be used to classify the liquid. Such a sensor is especially practical if it can be connected in-line with the liquid to be measured, thus minimally influencing flow. A piezoceramic tube was studied in an attempt to produce a sensor to encompass exactly those aims. Spectra were taken of liquid-filled piezoceramic tubes. Severalmodels for this system, both for the piezoceramic tube and the liquid within it, were then studied to determine an accurate mathematical representation of the measured spectra. The model ultimately used was a derived equation for the dynamics of the liquid. The simulated spectra were optimized to match the actual data, using several techniques ranging from simple search algorithms to breeder algorithms. The optimization technique used was based upon the complexity of the model implemented. The effect of the error calculation method is important and is discussed. From the optimization results, the speed of sound, density and viscosity of the liquid can be determined to accuracies of less than 0.2%, 3% and 10% respectively.
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Includes bibliographical references (leaves 102-105).
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Prenzlow, B. 2006. Ultrasonic spectroscopy of liquid filled piezoelectric tube. University of Cape Town.