Untersuchung von Einzel- und Mehrblasensystemen in akustischen Resonatoren

Abstract

Acoustically driven bubbles in a liquid perform volume oscillations and translational motion. In standing sound fields the bubbles form complex spatio-temporal structures (acoustic cavitation fields).Basic investigations are carried out on single bubble systems. The feedback of a single bubble on the driving system´s resonance is experimentally studied and a significant influence on the resonance frequency is measured. The translational dynamics in a weak sound field is calculated analytically under the assumption of linear volume oscillation. The bubble motion is also experimentally determined and compared with a numerical model under consideration of the viscous dragforce. Apart from qualitative investigations of the excitation of surface modes, single bubble sonoluminescence is realized in air-saturated water.Concerning multi bubble fields, the appearing spatial configurations can be subdivided into few classes. The characteristic properties of these structures are described and different experimental investigations are carried out. In particular, the influence of bubble sources, i.e. places where bubbles may be generated, on structure formation is studied. The velocity distribution in the bubble field at different driving amplitudes and the correlation between sound emission and structure formation in the cavitation field are investigated. Furthermore, high-speed cinematographic recordings of cleaning and erosion processes in acoustic cavitation fields are analyzed.