HYDRODYNAMIC PRESSURE MEASUREMENTS OF THE VERTICAL WATER ENTRY OF A SPHERE
NAVAL ORDNANCE LAB WHITE OAK MD
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The phenomena associated with the vertical water entry of 2-inch- diameter aluminum spheres striking the water surface at 28 feet per second were investigated by the use of hydrophones placed below the water surface. The pressure recordings from the hydrophones were analyzed for the three distinct phases of the water-entry problem namely, 1 impact phase, 2 cavity flow phase, and 3 cavity collapse. The impact phase was analyzed by means of a dipole theory and a momentum equation. The cavity flow phase was analyzed by the potential theory of a half-body placed in a uniform flow since the shape of the water-entry cavity is very similar to a half-body. A comparison of actual pressures recorded with those as predicted by the half-body theory show agreement within ten percent both outside and inside the cavity.
- Fluid Mechanics