The Experimental Installation for Studying the Effect of Ultrasound Frequency, Temperature and Hydrostatic Pressure on the Threshold Parameters of Ultrasonic Cavitation and its Progression

Acoustic cavitation can be used successfully to implement or intensify physical and chemical processes in liquids in a variety of emerging applications. The investigation of cavitation control methods will assist in the understanding of optimal ways of controlling the onset or prevention of cavitation in related applications. However, most previous experimental studies have concentrated on the cavitation process at specific ultrasound, liquid, hydrostatic pressure, and temperature parameters. Nonetheless, some experimental and theoretical studies show a significant relationship between the influence of these parameters on the onset and development of cavitation processes in liquids. This paper presents an installation for studying acoustic cavitation in various liquids at different ultrasound amplitude-frequency parameters, variable hydrostatic pressure, and temperature. The installation includes four reactors with ultrasound frequencies of 17, 22, 33, and 44 kHz. Ultrasonic waves are produced by a magnetostrictor transducer with a sonotrode immersed in the reactor's substance. The reactor's design allows for varying the hydrostatic pressure from 1 to 10 atm and heating the liquid to 80 °C. As an approval of the installation, the possibility of registering the threshold power of the transducer at the onset of cavitation was considered. The cavitation threshold was investigated using three different liquid loading modes: step-by-step transducer power increase, smooth transducer power increase, and smooth variation of hydrostatic pressure at constant transducer power. Water and sunflower oil were used in the tests. It was found that the installation allows for a study of the frequency dependence of the cavitation onset threshold as well as the effects of hydrostatic pressure and temperature. Specific examples and results are discussed. For example, the possibility of stable control of the onset and attenuation of cavitation by changing the hydrostatic pressure is shown. Furthermore, the results show that the optimal power of the ultrasonic transducer can be chosen based on the available combination of ultrasonic frequency, hydrostatic pressure, and temperature. Some next steps for the installation's development and research are also discussed.