Cavitation-induced shock wave behaviour in different liquids

Mohammad Khavari; Abhinav Priyadarshi; Justin Morton; Kyriakos Porfyrakis; Koulis Pericleous; Dmitry Eskin; Iakovos Tzanakis

doi:10.1016/j.ultsonch.2023.106328

Cavitation-induced shock wave behaviour in different liquids

Ultrason Sonochem. 2023 Mar:94:106328. doi: 10.1016/j.ultsonch.2023.106328. Epub 2023 Feb 14.

Authors

Mohammad Khavari¹, Abhinav Priyadarshi², Justin Morton², Kyriakos Porfyrakis³, Koulis Pericleous⁴, Dmitry Eskin⁵, Iakovos Tzanakis⁶

Affiliations

¹ School of Computing and Engineering, College of Science and Engineering, University of Derby, Derby DE22 3AW, United Kingdom; Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, United Kingdom. Electronic address: mkhavari@brookes.ac.uk.
² Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, United Kingdom.
³ Faculty of Engineering and Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, United Kingdom.
⁴ Computational Science and Engineering Group, University of Greenwich, 30 Park Row, London SE10 9LS, United Kingdom.
⁵ Brunel Centre for Advanced Solidification Technology, Brunel University London, Uxbridge UB8 3PH, United Kingdom.
⁶ Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, United Kingdom; Department of Materials, University of Oxford, Parks Rd, Oxford OX1 3PH, United Kingdom.

Abstract

This paper follows our earlier work where a strong high frequency pressure peak has been observed as a consequence of the formation of shock waves due to the collapse of cavitation bubbles in water, excited by an ultrasonic source at 24 kHz. We study here the effects of liquid physical properties on the shock wave characteristics by replacing water as the medium successively with ethanol, glycerol and finally a 1:1 ethanol-water solution. The pressure frequency spectra obtained in our experiments (from more than 1.5 million cavitation collapsing events) show that the expected prominent shockwave pressure peak was barely detected for ethanol and glycerol, particularly at low input powers, but was consistently observed for the 1:1 ethanol-water solution as well as in water, with a slight shift in peak frequency for the solution. We also report two distinct features of shock waves in raising the frequency peak at MHz (inherent) and contributing to the raising of sub-harmonics (periodic). Empirically constructed acoustic pressure maps revealed significantly higher overall pressure amplitudes for the ethanol-water solution than for other liquids. Furthermore, a qualitative analysis revealed that mist-like patterns are developed in ethanol-water solution leading to higher pressures.

Keywords: Bubble cloud; Shock wave; Ultrasonic cavitation.