LABORATORY SIMULATION OF UNDERWATER BLAST WAVES BY HIGH SPEED WATER ENTRY

Abstract

A method is presented for simulating underwater blast waves for unconfined laboratory experiments. High speed water entry of projectiles can create ballistic waves that resemble underwater blast waves. This paper provides several practical examples of launching projectiles downward into a 1000L container of water, a method accessible in many laboratories. Resulting ballistic waves are measured with a piezoelectric pressure transducer. Results are reported for four projectiles: 1) A 4.5 mm diameter steel sphere fired from a pump “bb gun” impacting at 199 m/s. 2) A 7.82 mm diameter hardened lead sphere fired from a 30/30 rifle impacting at 345 m/s. 3) A 5.59 mm diameter lead hollow point bullet fired from a .22 LR rifle impacting at 389 m/s. 4) A 9 mm diameter jacketed hollow point pistol bullet fired from a service caliber pistol impacting at 397 m/s. In all cases presented here, the ballistic waves generated in high speed water entry might find experimental use as simulated underwater blast waves, depending on experimental requirements. Peak blast magnitude ranged from 400 kPa to 2500 kPa, and positive pulse duration ranged from 0.2 ms to 0.6 ms. Wave shape varied in quality.