Putting cavitation to work: applications of strongly collapsing bubbles
Embargo Date
2024-08-26
OA Version
Citation
Abstract
Strongly collapsing bubbles, whose presence and activity are often conveniently captured by the word ‘cavitation’, can produce profound effects in the medium and mechanisms in which they are produced. The word ‘cavitation’ then implies bubble activity consistent with significant growth followed by strong detectable collapse. Such a definition is consistent with the notion that a ‘cavity’ in a liquid is, however created, essentially empty and behaves as such for the application at hand. This thesis covers three separate projects, all studying cavitation or phenomena observed due to cavitation. A sufficient background in mostly single bubble dynamics is provided as a basis for understanding cavitation and its associated phenomena. Particular attention will be paid to the theory presented by Lord Rayleigh, which predicts the interface and fluid velocities, the surrounding liquid pressure distribution, and the timing of growth and collapse of a strongly collapsing cavity.
Three particular applications of cavitation are presented in this thesis. Motivated by the observation that cavitation could, despite certain deleterious effects, enhance automotive engine fuel injector performance, experimental results using techniques of Passive Cavitation Detection (PCD), Optical Cavitation Detection (OCD), and Passive Cavitation Imaging (PCI) to detect cavitation inception and activity in nozzles are reported. Motivated by the need for a novel and non-contact means for exciting resonant vibrational modes of underwater objects leading to their subsequent identification, experimental results employing cavitation as the excitation mechanism are reported. Finally, motivated by recent studies of nanosecond high-pressure phase transitions in water, theoretical background and preliminary experimental work to employ cavitation to cause phase transitions is reported.