Different problems from cavitation are encountered in practice. Effects are mostly related to vibration, noise, erosion, changes in flow hydrodynamics, increase of hydrodynamic drag, light and thermal effects. Especially the former are still relatively unknown, but are of great significance due to high temperatures that occur on the micro scale level. On macroscopic level thermal effects become significant when dealing with liquids of temperature close to the critical temperatures. We will consider acoustic cavitation, where we will study thermodynamic effects of single bubbles. Cavitation will be generated with ultrasound in a small vessel. With aid of high-speed thermo camera analyses of local thermal effects in boundary layer that occur prior and post bubble collapse will be studied.
With measurements, which will be performed within the scope of the project, we will first determine and evaluate the thermodynamic effects, which will lead to better and more general simulation methods. On the basis of results conclusions on events that preceded the moment of measurement could be made. There will be a possibility to evaluate extreme conditions in cavitation bubble (temperature), which are at the present time estimated only on a basis of theoretical studies.
Acoustic cavitation, which is the subject of research is also used for different purposes in medicine (for example, at removal of the kidney stones – lithotripsy). Indirect research findings will serve for improvements in the use of different techniques.
|Temperatures during evolution of an ultrasonic cavitation bubble|
OSTERMAN, Aljaž, DULAR, Matevž, HOČEVAR, Marko, ŠIROK, Brane. Infrared thermography of cavitation thermal effects in water. J. mech. eng., 2010, vol. 56, iss. 9, pp. 527-534 [PDF]
OSTERMAN, Aljaž, DULAR, Matevž, ŠIROK, Brane. Numerical simulation of a near-wall bubble collapse in an ultrasonic field. J. fluid sci. technol., 2009, vol. 4, no. 1, pp. 210-221 [PDF]
Partners: Hidria Institute, Godovic, Slovenia
Duration: 2007 – 2009