HYDRA PROGRAM HYDRA IIB SERIES - INVESTIGATION BY WATER SAMPLING OF THE INTERNAL STRUCTURE OF COLUMNS RESULTING FROM SMALL SHALLOW UNDERWATER EXPLOSIONS

摘要

The internal structure of the columns from one-pound high-explosive shallow underwater explosions has been investigated by means of water sampling for several shallow charge depths. Water samples taken at varying times across the column diameter at several heights up to 8 ft are used to compute the thickness of the water seal between the explosion product gas bubble and the air of the initial column formation and the total volume of water ejected into the column. These are compared with computed seal thickness and water volume assuming outward flow of the water over the charge to be only radial in direction. Sampling data is used along with above-and below-surface photographs to construct a time sequence of the column structure for charge depths of 5.5 and 12 in. It is shown that true radial flow of water over the charge occurs only during the very early initial bubble expansion and is soon supplanted by a tangential flow which converges well above the surface. The converging water results in both an upward jet which rises high into the air and a downward jet which penetrates through the underwater bubble.