Deformation Behavior of Dirt in Cleaning by Gas-Liquid Two-Phase Pulsating Jet

Jet cleaning is a method used for various applications, such as oil cleaning and oral cavity cleaning, and many studies have been conducted on methods to improve cleaning capability. However, there are few studies focused on the behavior of dirt by jet cleaning, and the removal process has not been clarified. In this study, gas-liquid two-phase pulsating jet is focused on and the deformation behavior of dirt by this jet was investigated with detailed visualization. Silicon oil of various viscosities was used as simulated dirt. It was found that the impact of the jet stream on the dirt deforms the dirt into a crater shape. In gas-liquid two-phase pulsating jets, where there are many bubbles and voids in the jet, fine fluctuations in collision pressure were observed, and it is certain that craters quickly reach the baseplate due to continuous flow inside the sample. Detailed visualization and measurement of this behavior confirmed that cleaning proceeds in two stages: “crater formation process by jet intrusion” before the crater reaches the baseplate, and “crater expansion process by diffusion flow” after the crater reaches the baseplate.