engleski

Measuring acoustic power of low-frequency ultrasound devices by using calorimetric method and electromechanical characterization

In this work the acoustic power of ultrasound low-frequency device with three different types of sonotrode tips has been measured by using two different method suggested in international standards IEC 61847 and 61088. Some of suggested methods do not include the effect of a strong cavitation activity in front of the sonotrode tip and positions of the tip in the complex standing wave pattern in the vessel where measurements are done. In this work, results of two different methods for characterization of the device have been compared in the term of electroacoustic efficiency factors. The dissipated acoustic power has been measured in a calorimetric configuration at two different immersion depths by using different applied electrical excitation levels into the piezoceramic elements. The removable sonotrode tips are used with the aim to see how the dissipated acoustic power depends on the size and shape of the sonotrode tip which cause different strength of cavitation activity in front of the tip. The second method considered in this work is the electromechanical characterization, which consists of measuring the input electrical impedance of unloaded and loaded ultrasonic device and determination of the equivalent electrical circuits and radiated acoustic power in the loading medium. A significant difference in the input electrical impedance measurements results and calculated electroacoustic efficiency factors is observed when the tips are located at different positions in the vessel during electromechanical characterization. Cavitation activity significantly increases the input electrical impedance magnitude at excitation frequency as compared to the value measured at 1V excitation voltage magnitude. The electroacoustic efficiency factor of the calorimetric method is in the range between 60-70% for all excitation levels.

low-frequency ultrasound device; equivalent electrical circuit; electroacoustic efficiency factor; calorimetric method

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