# Dynamic Simulation Model and Performance Optimization of a Pressurized Pulsed Water Jet Device
###### Abstract  
Pulsed water jet technology has broad application prospects in the field of rock breaking. The pressurized pulsed water jet (PPWJ) is a new type of pulsed jet that offers high-amplitude pressurization, variable pulse pressure and frequency, and a high energy usage rate. To achieve a more destructive and powerful pulsed water jet, a dynamic simulation model of the device was established by using the AMESim software (v1400) based on the operational principle of PPWJs, and the simulation model was validated against the experimental results. The relationships between the key structural parameters of the PPWJ device and the pulse parameters were quantitatively investigated. The pulse pressure and frequency can be increased by appropriately increasing the nozzle diameter or boost ratio, and the pulse pressure will drop if the nozzle diameter or boost ratio exceeds a threshold value. Increasing the maximum displacement or action area of the piston will increase pulse length while decreasing pulse frequency; a proper match of the maximum displacement or action area of the piston will assure pulse peak pressure. The maximum outer diameter of the piston only affects the pulse frequency. The key structural parameters of the device were optimized on that foundation. Compared to the original device, the optimized device resulted in an increase in pulse frequency and jet output energy, leading to larger diameter and volume of erosion pits at the same stand-off distance and erosion time. The findings of this study offer valuable scientific insights for achieving efficient rock breaking with PPWJ. pulsed water jet; pulse parameters; dynamic simulation; optimal design; rock breaking +
Footnote †: journal: Applied  
characteristics of the flow field, and the oscillation mechanism. [PERSON] et al. [14; 15; 16] studied the effect of nozzle inner surface roughness, inlet area discontinuity, and feed pipe diameter on the erosion performance of the SOPWJ jet. [PERSON] et al. [17] and [PERSON] et al. [18] investigated the velocity and pressure characteristics of a SOPWJ through modifications in the structural parameters of the nozzle and the operational parameters of the system, respectively. [PERSON] et al. [19; 20; 21] introduced the gas-spring theory to elucidate the oscillation mechanism of SOPWJ, and it was found that the oscillating frequency is predominantly controlled by the cavitation clouds in the chamber. [PERSON] et al. [22] studied the asymmetric flow and sustained oscillation phenomena of fluid in a symmetric cavity under high-Reynolds-number and high-cavity-diameter-ratio conditions through numerical simulation. [PERSON] et al. [23] highlighted the importance of tool geometry and changes in water pressure at the inlet to the self-excited pulsating heads and the dynamics of the PWJ. Nevertheless, the pulse parameters and operational performance of a SOPWJ are challenging to regulate owing to its high sensitivity to supply pressure and nozzle structure. Furthermore, the pulse pressure typically falls short of 40 MPa, rendering it inadequate for breaking hard rocks. Another type of PWJ is the ultrasonically modulated pulsed water jet (UMPWJ) that utilizes ultrasonic waves to create pulses with high frequency, which was first proposed by [PERSON] [24]. On this foundation, [PERSON] et al. [25] found that the cutting depth of the UMPWJ was significantly greater than that of the CWJ, and the grooves formed were more regular. [PERSON] et al. [26] applied the shadowgraph technique and particle tracking velocimetry processing algorithms to visualize the UMPWJ structures and velocity vector fields. [PERSON] et al. [27] and [PERSON] et al. [28] demonstrated that the erosion performance of UMPWJ surpasses that of a CWJ operating at the same parameters. [PERSON] et al. [29] and [PERSON] et al. [30] conducted a cutting experiment on sandstone with a UMPWJ. The results of the experiment indicated that the pulse frequency has a significant effect on the depth, width, and volume of the groove. [PERSON] et al.