Sonoluminescence and dynamics of cavitation bubble populations in sulfuric acid

Abstract

The detailed link of liquid phase sonochemical reactions and bubble dynamics is still not sufficiently known. To further clarify this issue, we image sonoluminescence and bubble oscillations, translations, and shapes in an acoustic cavitation setup at 23kHz in sulfuric acid with dissolved sodium sulfate and xenon gas saturation. The colour of sonoluminescence varies in a way that emissions from excited non-volatile sodium atoms are prominently observed far from the acoustic horn emitter ("red region"), while such emissions are nearly absent close to the horn tip ("blue region"). High-speed images reveal the dynamics of distinct bubble populations that can partly be linked to the different emission regions. In particular, we see smaller strongly collapsing spherical bubbles within the blue region, while larger bubbles with a liquid jet during collapse dominate the red region. The jetting is induced by the fast bubble translation, which is a consequence of acoustic (Bjerknes) forces in the ultrasonic field. Numerical simulations with a spherical single bubble model reproduce quantitatively the volume oscillations and fast translation of the sodium emitting bubbles. Additionally, their intermittent stopping is explained by multistability in a hysteretic parameter range. The findings confirm the assumption that bubble deformations are responsible for pronounced sodium sonoluminescence. Notably the observed translation induced jetting appears to serve as efficient mixing mechanism of liquid into the heated gas phase of collapsing bubbles, thus potentially promoting liquid phase sonochemistry in general.

Leuchtende Blasen

“…Tatsächlich zeigten sich bei genauerer Untersuchung solcher Natrium‐Emissionsbereiche, dass relativ große Blasen dort entweder Oberflächeninstabilitäten entwickeln, oder dass sie sich schnell bewegen und mit einem internen Flüssigkeitsstrahl (Jet) kollabieren . Die Jetbildung ist ein fundamentales Phänomen bei einer rasch bewegten, kollabierenden Blase und in der Tat ein Vorgang, der Flüssigkeit ins Blaseninnere einträgt (s. „Blasenbewegung und Jet“ im Zusatztext).…”

Acoustic characterization of cavitation intensity: A review

“…Cavitation usually refers to the generation of cavities and the subsequent dynamic behaviors when a liquid suffers from a sufficient pressure drop [1] . Due to high temperature and pressure [2] , [3] , [4] , [5] , micro jet [6] , [7] , [8] , shock wave [9] , [10] , [11] , light emission [12] , [13] , [14] and derived biochemical effects [15] , [16] , [17] in the process of cavitation, cavitation has been widely used in many fields, such as sonochemistry [18] , [19] , [20] , [21] , environmental engineering [22] , [23] , [24] , [25] , biomedical engineering [26] , [27] , [28] , material science [29] , [30] , [31] , [32] , food processing [33] , [34] , [35] , and so on. To estimate the cavitation effects and monitor the conditions of cavitation processes, cavitation detection and intensity characterization are desired.…”

Modeling the Voltage Produced by Ultrasound in Seawater by Stochastic and Artificial Intelligence Methods

“…Effects as corrosion-erosion [6][7][8], the apparition of vibration and noise [9][10][11], sonoluminescence [12], and solid materials' unpassivation are associated with the ultrasonic cavitation. Ultrasonic cavitation is employed for bleaching, soldering, emulsification, cleaning, extraction, nanoparticles synthesis, and separation [3,9].…”