Dynamics of laser-induced cavitation bubbles near a short hole and laser cavitation processing with particles

Abstract

The interest in pulsation process of laser-induced cavitation bubble in infinite domain or near a solid boundary has increased greatly in recent years. However, studies on dynamics of laser-induced bubbles near a small hole are few. In this work, dynamics of laser-induced cavitation bubbles before and after going through a small hole was studied by high-speed imaging. Various dimensionless parameter, laser energies, hole diameters and hole lengths were selected to investigate the bubble pulsation. Furthermore, a novel surface treatment method of small hole assisted laser cavitation processing in SiO2 particles suspension was proposed to improve surface quality. The surface morphology, residual stress, and roughness of 1060 aluminium alloy after laser cavitation processing were investigated. Results indicate that dimensionless parameter and hole’s size have a great impact on bubble pulsation. Maximum instantaneous velocity of the front and rear walls of the bubbles is about 47 m/s and 119 m/s respectively when the bubble pulsates behind the hole. The movements of the bubbles may cause the particles to impact the surface, producing small hollows and providing concentrated residual stress.