Session AJ: Bubbles I: Cavitation

8:00 AM–9:57 AM, Sunday, November 22, 2009
Room: 101I

Chair: Roger Arndt, University of Minnesota

Abstract ID: BAPS.2009.DFD.AJ.8

Abstract: AJ.00008 : Cavitation induced by high speed impact of a solid surface on a liquid jet

9:31 AM–9:44 AM

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  Mohamed Farhat
    (Ecole Polyechnique Federale de Lausanne)

  Marc Tinguely
    (Ecole Polyechnique Federale de Lausanne)

  Mathieu Rouvinez
    (Ecole Polyechnique Federale de Lausanne)

A solid surface may suffer from severe erosion if it impacts a liquid jet at high speed. The physics behind the erosion process remains unclear. In the present study, we have investigated the impact of a gun bullet on a laminar water jet with the help of a high speed camera. The bullet has a flat front and 11 mm diameter, which is half of jet diameter. The impact speed was varied between 200 and 500 ms$^{-1}$. Immediately after the impact, a systematic shock wave and high speed jetting were observed. As the compression waves reflect on the jet boundary, a spectacular number of vapour cavities are generated within the jet. Depending on the bullet velocity, these cavities may grow and collapse violently on the bullet surface with a risk of cavitation erosion. We strongly believe that this transient cavitation is the main cause of erosion observed in many industrial applications such as Pelton turbines.

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