Rock cutting by pulsing water jets

Generation of pulsations in high-speed water jets enables to increase the cutting performance of water jets due to the fact that the impact pressure generated by an impact of slug of water on the target material is considerably higher than the stagnation pressure generated by corresponding continuous jet. Highly complex dynamics of the flow of pulsating water jet was studied at the Institute of Geonics in Ostrava both theoretically with aid of CFD methods and experimentally using methods of direct measurement of pressure pulsations and impact forces generated by the jet. Cutting effects of pulsing water jets were tested extensively in laboratory to verify their performance in hard rock cutting. Interaction of the pulsing jet with rock material was studied using image analysis to define processes occurring during the interaction as well as the influence of the pulsing jet on newly created rock surface. In this paper, selected results obtained during laboratory tests of cutting of rocks by pulsing water jets are presented. Tests were performed on basalt, sandstone and granite samples and performance of the pulsing water jet was compared with the performance of continuous one under the same testing conditions.