Cavitation Bubble Dynamics In Isolated Water Drops In Microgravity
- Paper number
IAC-06-A2.3.05
- Author
Mr. Danail Obreschkow, European Space Agency/Student Participation Programme, United Kingdom
- Year
2006
- Abstract
The hydrodynamic cavitation phenomenon is a major source of erosion for many industrial systems such as cryogenic pumps for rocket propulsion, fast ship propellers, hydraulic pipelines and turbines. Erosive processes are associated with liquid jets and shockwaves emission following the cavity collapse. Yet, the relative importance of these two processes remains controversial and this issue requires further cavitation studies inside various geometries of liquid volumes. In particular, one might fruitfully consider bubbles inside spherical isolated water volumes, which is hardly achievable on Earth due to the presence of gravity. We performed an experimental study of single bubble dynamics inside quasispherical water drops produced in microgravity (Parabolic Flights, European Space Agency ESA). High-speed imaging revealed the implications of isolated, finite liquid volumes and spherical free surfaces on the bubble collapse and subsequent phenomena. In particular, (A) toroidally collapsing bubbles close to free surfaces eject two liquid jets escaping from the drop in antipodal directions. (B) Bubble lifetimes are shorter than in extended volumes in accordance with a novel Rayleigh-Plesset-type equation for bubbles in finite spherical drops. (C) The spherical free surface leads to a broader counterjet than previously studied flat free surfaces. (D) Bubble induced shock waves are spatially confined, which amplifies the formation of transient microbubbles. We use this feature as a novel way of recovering shock wave energies in isolated liquid volumes. A second participation at parabolic flights (Professional Flight Campaign, ESA, March 2006) will serve to focus on the shockwave-nuclei interactions and to obtain direct shockwaves visualizations. More specifically, sharper images will be achieved by the addition of an ultra-short flashlight, and artificial gaseous nuclei will be introduced in the water volumes.
- Abstract document
- Manuscript document
IAC-06-A2.3.05.pdf (🔒 authorized access only).
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