Further Study of the Generation Technique of High-Speed Liquid Jets and Related Shock Wave Phenomena Using a Helium Gas Gun

Abstract

An extensive experimental investigation was carried out with the aim of understanding the hydrodynamics involved in generating a pulsed high-speed liquid jet. A wire cutting device for measuring the projectile velocity was installed at the exit section of the launch tube so that the impact velocity of projectiles and the velocity of liquid jets could be measured simultaneously. The projectiles were made from low-density polyethylene, which was expected to reduce the rebound in the impact and thus to create a a high nozzle pressure for a longer duration. The jets were generated using different combinations of nozzle diameters, impact methods, nozzle back side geometries, light and heavy projectiles, etc. Based on the obtained relationships between the jet velocities and projectile velocities, the hydrodynamic processes occurring in the nozzles were clarified to some extent. Besides the liquid jet experiment, the projectile motion along the launch tube, in-tube shock wave and discharging shock wave were also examined in order to improve the performance of the gas gun and to calibrate the laser system. The results of theoretical analyses and numerical work were applied to interpret the experiment results.