Shock Waves (2013) 23:105–114 DOI 10.1007/s00193-013-0431-1 ORIGINAL ARTICLE Characteristics of impact-driven high-speed liquid jets in water A. Matthujak · C. Kasamnimitporn · W. Sittiwong · K. Pianthong · K. Takayama · B. E. Milton Received: 11 January 2012 / Revised: 4 October 2012 / Accepted: 1 February 2013 / Published online: 15 February 2013 © Springer-Verlag Berlin Heidelberg 2013 Abstract This paper describes a preliminary investigation of the characteristics of high-speed water jets injected into water from an orifice. The high-speed jets were generated by the impact of a projectile launched by a horizontal single- stage powder gun and submerged in a water test cham- ber. The ensuing impact-driven high-speed water jets in the water were visualized by the shadowgraph technique, and the images were recorded by a high-speed digital video camera. The processes following such jet injection into water, the jet-induced shock waves, shock wave propaga- tion, the bubble behavior, bubble collapse-induced rebound shock waves and bubble cloud re-generation were observed. Peak over-pressures of about 24 and 35GPa measured by a Polyvinylidence difluoride (PVDF) piezoelectric film pres- sure sensor were generated by the jet impingement and the bubble impingement, respectively. The peak over-pressure was found to decrease exponentially as the stand-off dis- Communicated by E. Timofeev. A. Matthujak (B ) · C. Kasamnimitporn Combustion and Jet Application Research Laboratory (CJARL), Department of Mechanical Engineering, Faculty of Engineering, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand e-mail: Anirut.Mat@gmail.com; A.Matthujak@ubu.ac.th W. Sittiwong · K. Pianthong Department of Mechanical Engineering, Faculty of Engineering, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand K. Takayama Shock Wave Interdisciplinary Application Division, Institute of Fluid Science, Tohoku University, 2-1-1, Katahira, Sendai 980-8577, Japan B. E. Milton School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, Australia tance between the PVDF pressure sensor and the nozzle exit increases. Keywords Impact-driven high-speed water jet · Shadowgraph · Shock wave · Bubble · Over-pressure 1 Introduction High-speed liquid jets have been experimentally and the- oretically studied [1–3] for their wide applications, such as cleaning and cutting technologies, mining and tunnel- ing [4–8]. The high-speed liquid jets have also gained attention in combustion [9, 10] and medical applications [11–13], such as drug injection, tissue cutting and the removal of a cerebral thrombus. Recently, attention has begun to be focused on industrial applications of jets to underwater work [14], such as cutting marine struc- tures and drilling at the sea bottom, the energy density of these high-speed jets being sufficiently high for these processes. In 1995, Obara et al. [15] investigated the mechanisms of the liquid-jet impact on liquid. In this study, a water jet of 3 mm diameter, generated using a single impact jet appa- ratus, impacted at 600m/s on the surface of water. In the impact upon a water surface, a cavitation bubble cloud gen- erated at the central axis of the liquid jet and the release wave produced by the reflection of the shock wave at the interface were visualized using the shadowgraph technique. Moreover, they found that the generation of the cavitation bubble and its rapid collapse might contribute to damage. That was because the bubble collapse might produce local- ized pressure concentrations on a material surface due to microjet impact. However, the behaviors of a jet-generated 123