Scale up design study on process vessel dimensions for ultrasonic processing of water and liquid aluminium

Mohammad Khavari; Abhinav Priyadarshi; Tungky Subroto; Christopher Beckwith; Koulis Pericleous; Dmitry G Eskin; Iakovos Tzanakis

doi:10.1016/j.ultsonch.2021.105647

Scale up design study on process vessel dimensions for ultrasonic processing of water and liquid aluminium

Ultrason Sonochem. 2021 Aug:76:105647. doi: 10.1016/j.ultsonch.2021.105647. Epub 2021 Jun 23.

Authors

Mohammad Khavari¹, Abhinav Priyadarshi², Tungky Subroto³, Christopher Beckwith⁴, Koulis Pericleous⁴, Dmitry G Eskin⁵, Iakovos Tzanakis⁶

Affiliations

¹ Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, UK; Department of Materials, University of Oxford, Parks Rd, Oxford OX1 3PH, UK. Electronic address: mkhavari@brookes.ac.uk.
² Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, UK.
³ Brunel Centre for Advanced Solidification Technology, Brunel University London, Uxbridge UB8 3PH, UK.
⁴ Computational Science and Engineering Group, University of Greenwich, 30 Park Row, London SE10 9LS, UK.
⁵ Brunel Centre for Advanced Solidification Technology, Brunel University London, Uxbridge UB8 3PH, UK; Tomsk State University, 36 Lenin Avenue, Tomsk 634050, Russia.
⁶ Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, UK; Department of Materials, University of Oxford, Parks Rd, Oxford OX1 3PH, UK. Electronic address: itzanakis@brookes.ac.uk.

Abstract

Scaling up ultrasonic cavitation melt treatment (UST) requires effective flow management with minimised energy requirements. To this end, container dimensions leading to the resonance play a crucial role in amplifying pressure amplitude for cavitation. To quantify the importance of resonance length during the treatment of liquid aluminium, we used calibrated high-temperature cavitometers (in the range of 8-400 kHz), to measure and record the acoustic pressure profiles inside the cavitation-induced environment of liquid Al and deionized water (used as an analogue to Al) excited at 19.5 kHz. To achieve a comprehensive map of the acoustic pressure field, measurements were conducted at three different cavitometer positions relative to the vibrating sonotrode probe and for a number of resonant and non-resonant container lengths based on the speed of sound in the treated medium. The results showed that the resonance length affected the pressure magnitude in liquid Al in all cavitometer positions, while water showed no sensitivity to resonance length. An important practical application of UST in aluminium processing concerns grain refinement. For this reason, grain size analysis of UST-treated Al-Cu-Zr-Ti alloy was used as an indicator of the melt treatment efficiency. The result showed that the treatment in a resonance tank of L=λ_Al (the wavelength of sound in Al) gave the best structure refinement as compared to other tested lengths. The data given here contribute to the optimisation of the ultrasonic process in continuous casting, by providing an optimum value for the critical compartment (e.g. in a launder of direct-chill casting) dimension.

Keywords: Aluminium casting; Cavitation; Resonance length; Spectral analysis; Ultrasonic processing.