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  • High speed observation of d...
    Dular, Matevž; Požar, Tomaž; Zevnik, Jure; Petkovšek, Rok

    Wear, 01/2019, Letnik: 418-419
    Journal Article

    One of the remaining open questions in cavitation erosion research is the one on the importance of the microjet and the shock wave on the formation of the pit. Up until now, no successful attempt has been made to study this in detail, mainly because the damage could only be detected and evaluated after several successive bubble collapses. A bubble with a maximum diameter of up to 3.3 mm was created during photoionization using a Nd:YAG laser. The damage was observed on a 9 µm thick aluminum foil attached to a glass substrate. Two high speed cameras were simultaneously used. One captured the dynamics of the bubble, while the other recorded the damage of the foil. We also observed the collapse of a bubble in the presence of shear flow, where most of the damage is created by the microjet mechanism. Sometimes, the collapse of the bubble rim, at the rebound of the initial bubble causes pits in a well-known circular pattern. From the recordings at the very fastest acquisition rate, we determined that the material deforms and then partially relaxes, while a significant deformation remains. The whole process is only 2–3 µs long. Display omitted •Cavitation damage from a single bubble was observed.•Pit formation during 3 μs was measured.•Shear flow influence on erosion was determined.•Importance of microjet and shock wave was determined.