High Speed Observation of Periodic Cavity Behavior in a Convergent-Divergent Nozzle for Cavitating Water Jet

Keiichi Sato, Yuta Taguchi, Shota Hayashi

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Department of Mechanical Engineering, Kanazawa Institute of Technology, Nonoichi, Japan.

DOI: 10.4236/jfcmv.2013.13013                

Abstract

Cloud cavitation shows an unsteady periodic tendency under a certain flow condition. In a cavitating water jet flow with cavitation clouds, the cavities or the clouds produce high impact at their collapse. In order to make clear a mechanism of the periodic cavity behavior, we experimentally examine the behavior in a transparent cylindrical convergent-divergent nozzle using a high-speed video camera. An effect of upstream pressure fluctuation due to a plunger pump is investigated from a
viewpoint of unsteady behavior in a cavitating water jet. As a result, it is found that the cavitating flow has two kinds of oscillation patterns in the cavity length (cavitation cloud region). One is due to the upstream pressure fluctuation caused by the plunger pump. The other is much shorter periodic motion related to the characteristic oscillation of cavitation clouds accompanied with the shrinking (reentrant), growing and shedding motion of the clouds.

Keywords

Cloud Cavitation; Periodic Behavior; Water Jet; High-Speed Video Observation; Image Analysis

Conflicts of Interest

The authors declare no conflicts of interest.

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