Effects of each operating condition on the underwater shock waves driven by imploding detonation and microorganism treatment experiments

Abstract

In recent years, microorganisms contained in ship ballast water have been identified as vectors for the destruction of marine ecosystems. To control such microorganisms, various techniques are being developed and tested. As part of this effort, we propose a technique that uses underwater shock waves driven by a gas-imploding detonation. Previously, we have reported characteristics of pressure generation at the implosion center of an imploding detonation. Subsequently, we installed a nozzle at the implosion center of an underwater shock wave generating apparatus and measured how characteristics of underwater shock waves responded to changes in operating conditions. Operating conditions were manipulated by changing the inner diameter of the nozzle, the initial pressure, the equivalence ratio, and the nitrogen concentration in the premixed gas. We examined how the maximum pressure, rise time, half-width time, and shock energy of underwater shock waves affected the mortality rate of microorganisms (Artemia salina). We found that when the inner diameter of the nozzle was increased, the rise time and half-width time decreased, and the maximum pressure and shock energy increased. When the initial pressure and equivalence ratio were increased, the maximum pressure and shock energy increased, the rise time became shorter, and the half-width time became longer. When the nitrogen concentration was increased, the rise time became longer, and the half-width time became shorter. The mortality rate of Artemia salina was increased by shortening the rise time of the pressure waves while increasing the maximum pressure, the half-width time, and the shock energy of the underwater shock waves.

Keywords

• imploding detonation
• shock high pressure
• equivalence ratio
• diluent
• underwater shock wave
• microorganisms