University of Illinois Urbana-Champaign

An experimental study on the collapse of an air-filled cylindrical cavity under dynamic loading

Shpuntova, Galina V

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SHPUNTOVA-DISSERTATION-2018.pdf

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https://hdl.handle.net/2142/102451

Description

Title
An experimental study on the collapse of an air-filled cylindrical cavity under dynamic loading
Author(s)
Shpuntova, Galina V
Issue Date
2018-12-04
Doctoral Committee Chair(s)
Dutton, J. Craig
Committee Member(s)
  • Shepherd, Joseph E
  • Bodony, Daniel J.
  • Lambros, John
Department of Study
Aerospace Engineering
Discipline
Aerospace Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2019-02-06T19:36:21Z
Keyword(s)
  • Fluid mechanics
  • Multiphase
  • Bubbles
  • Bubble collapse
  • Cavitation
  • Wave-bubble interaction
  • Shadowgraph
  • Particle Image Velocimetry (PIV)
Abstract
A model system was designed and investigated experimentally to gain insight into the interactions of an air-filled cylindrical bubble immersed in hydrogel, a compliant boundary, and a transient loading wave. This combination is an analog of processes that occur in biomedical applications such as shockwave lithotripsy. No-boundary, rigid boundary, and two-boundary cases were also investigated. A transient pressure wave of 20~MPa peak magnitude generated by projectile impact was used to initiate bubble collapse. Ultra high-speed video recordings of the process showed the development of a re-entrant jet characteristic of asymmetric bubble collapse in the no-boundary case, but less frequent occurrence of this behavior in cases with boundaries. Void interface velocity in excess of 200~m/s was detected, which is sufficient to cause pressures in the hundreds of megapascals and possibly damage tissues. However, an alternative damage mechanism is also proposed based on the significant deformation of the upstream boundary during the collapse time. Flowfield data for all cases were acquired by a particle image velocimetry technique to elucidate the causes of boundary deformation, the suppression of jet formation, and the extreme velocities on the upstream void interface. An analytical model for the flow was developed to describe these flowfields, incorporating three components: the free-stream flow, a source flow, and a doublet flow. Parameters of the model were determined by fitting to data. The model represented the data to within 5~m/s on average---this was approximately equal to the 1-pixel PIV system noise threshold, and 5\% of the maximum flowfield velocity. The variation of model parameters over the course of the collapse was investigated to give the model predictive as well as descriptive value. The source strength agreed well with predictions based on symmetrical collapse relations. The doublet strength was consistent with the generation of vorticity on the bubble boundary due to interaction with a weak shock.
Graduation Semester
2018-12
Type of Resource
text
Permalink
http://hdl.handle.net/2142/102451
Copyright and License Information
Copyright Galina V Shpuntova 2018

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Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Aerospace Engineering