Numerical simulation and analysis on the flow field structure and hard rock erosion potential of a disc-slotted pulse water jet

A disc-slotted pulse water jet is a potential tool to break hard rock due to its special loading styles, such as the water hammer pressure, ultra-speed lateral jetting and pulse dynamic load etc. Aiming at investigating the flow filed of the jet, a two-phase-flow transient computational model, matching with the geometry and motion of the interrupted water jet generating device, was established to simulate the dynamic evolution and characteristics of a single pulsation within 100 mm standoff based on the volume of fluid (VOF) model and dynamic mesh theory. The results show that at the head of the pulsed jet forms a deflective slug structure which is consistent with the result from high-speed photography experiments. The slug head velocity is lower than that at the jet outlet and the jet turbulence is mainly distributed over boundary layers between jet and air and at the deflective side. Tile-shaped stereo-structure is yielded during the pulse formation process. It presents non-axisymmetric flow pattern when impacting target, which consists with the irregular erosion cavity obtained by hard rock fragmentation experiments.