Observation of cavitation in hydraulic oil flow separated from a smooth surface on which an incipient cavity is unable to stay

Seiichi Washio, Satoshi Takahashi, Shuichi Yoshimori

Research output: Contribution to journalArticle

Abstract

Cavitation has been observed in a hydraulic oil flow separated from a smooth cylindrical wall, using various methods such as a microscope mounted with either a digital still camera or a high-speed video one, laser beam transmission, photo-multiplier and an electric charge detector. At the incipient phase of cavitation, a cavity suddenly emerged at the separation point with its upstream tip attached on the wall. Differently from cavitation previously observed in such flows as separated from an edge or a projection, however, the present incipient cavity neither stayed nor made a stable bubble on the wall, which was smooth this time. While drifting downstream, the newly born cavity was substantially enlarged, underwent severe deformation and ultimately vanished from the tail in as short a time as one-tenth of milli-second. When being enlarged, the cavity emitted flashing light similar to the one formerly observed in the cavitation on the needle projection. Transient electric charge synchronized with the light emission was also detected from the oil in the downstream. Moreover, the streamline extending from the separation point was spontaneously visualized, indicating heat generation at the separation point where significant shear stress acts. All these results seem to support the "rip-off" hypothesis previously advocated by the present authors.

Original languageEnglish
Pages (from-to)1120-1127
Number of pages8
JournalNippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Volume69
Issue number681
DOIs
Publication statusPublished - May 2003
Externally publishedYes

Keywords

  • Cavitation
  • Electrostatic Charge
  • Hydraulic Oil Flow
  • Inception
  • Laser Beam Transmission
  • Non-stationary Cavity
  • Rip-off Hypothesis Light Emission
  • Visualized Streamline

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering

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