Transient Cavitation by Quick Closing Pincers
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Published:2018
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A mechanical device that mimics the snapping-claw mechanism of alpheid shrimps was developed to study experimentally transient cavitation. The apparatus consists of a pair of clamps (jaws), each with an inner contour that conforms to a half-Venturi geometry. One of the jaws is rigidly attached between two optically transparent parallel plates (forming a socket) and the other one works on a pivot. The clamps are mounted in such a way that when they close a Venturi tube-like with open and closed ends is formed. For the experiments, the device was immerse a few centimeters under tap water at lab conditions. The pivoting jaw was locked into an open position; then, its rapid closing was triggered mechanically and was driven by the contraction of rubber bands. High-speed video was used to capture the characteristics of the flow induced by the sudden relative motion between clamps. A water jet formed along with a variety of cavitation structures, such as cloud shedding, vapor lobes, travelling vortex rings, and bubble clouds were revealed. The developed technique could be an inexpensive alternative to test the performance of different Venturi geometries in cavitation regimes without the need for pipes, valves, tanks, and pumps typically used in experiments with hydraulic circuits.