Study on the cavitation mechanism in hydraulic oil flow using a needle projection

S. Washio, S. Takahashi, S. Kawahara, M. Kishitani

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Cavitation occurring at a sharp projection in a hydraulic oil flow was observed in as much detail as possible, using, variously, a microscope, a high-speed video camera, laser beams, an electric charge detector and a photomultiplier. At the tip of the needle employed as a projection, a tiny cavity as small as several tens of micrometres in length suddenly emerged and would not go away. As cavitation became more vigorous, flashes occurred intermittently around the needle and positive electrical charges were generated which synchronized with the flashing. The electrode inserted downstream from the needle detected negative charge from the oil, which was also synchronous with the flashing. Observing the needle tip with the microscope made it possible to determine exactly the moment of cavitation inception, which turned out to depend on the oil temperature as well as the downstream pressure. All these findings tend to reinforce the 'rip-off' hypothesis previously proposed by the present authors for the cavitation mechanism.

Original languageEnglish
Pages (from-to)27-34
Number of pages8
JournalProceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology
Issue number1
Publication statusPublished - 2002


  • Cavitation inception
  • Electric charge and discharge
  • Hydraulic oil flow
  • Light emission
  • Needle
  • Stationary cavity

ASJC Scopus subject areas

  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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