Numerical modelling of percussion water jets driven by multiple collisions

Abstract

A numerical model is proposed in this research to analyse the behaviour of the pulse jet driven by percussion hammer. The mass of the hammer is usually larger than that of the piston and the resistance of compressed water can low down the piston, thus multiple collisions occur each time when the hammer strikes the piston. The proposed model has the merit to consider various striking possibilities to simulate the process of pulse water jet generated by multiple hammer collisions. In addition, a hammer-driven percussion pulse jet is developed and the corresponding experiments are carried out for verifying the reliability of the numerical model. Comparison results show that the predicted pressure and velocity values match well with the experimental data. The simulation of the generation of pulsed jet reveals the collisions and motions of the hammer and the piston and provides understanding of the mechanism of the pulse jet generation. The design of the hammer-driven pulse water jet device can be optimised through modelling different combinations of the parameters of the chamber, hammer, piston and nozzle for a specific purpose of rock fragmentation.

Influence of Hydraulic Parameters on Multi-Stage Pulse Characteristics of Pressurized Pulsed Water Jet

“…High-speed photography is a technology that can effectively diagnose and test the jet. Ding et al [17] quantitatively measured the diffusion trajectory of the jet concentration field based on image analysis technology, Li et al [18] observed the change law of jet head penetration velocity into the water protective layer based on flash X-ray photography, Ye Yan et al [19] used high-speed photography and pulse coaxial holography to diagnose the dynamic image of micro jet head, Liu et al [20] used high-speed photography and postprocessing technology to study the spray characteristics of the nozzle plume at different stages, Lu et al [21] used high-speed photography to capture the evolution process of the drop hammer impact pulsed water jet in the flow field, and A. Matthujak et al [22] used aerial photography and shadow technology to visualize the impact-driven high-speed jet. Zdenek Riha et al [23] used photography technology to compare and analyze the structural characteristics of acoustic-wave-excited pulsed water jets and continuous water jets.…”