High speed photographic investigation of the first bubble period created by an underwater explosion.

Abstract

A relatively safe and inexpensive method was developed for the investigation of the oscillating bubble caused by the hot gases from an underwater explosion. High speed photography was employed to record the pulsations of the bubble caused by the detonation of decigram center-detonated spherical charges of P.E.T.N. Timing marks on the film were used to record the time interval or period of each oscillation. A description of the equipment constructed and used in the investigation is included in the body of the report. Calculations were carried out using the bubble period data and a semi-empirical equation with a rational basis to arrive at the relative underwater explosive strength of P. E.T.N, and T,N.T. Results obtained and recommendations for future work are offered in the last part of the report. Photographs of the entire sequence of events of an underwater explosion from detonation to the collapse of the second bubble are included as a appendix to this report.