Comparative Analysis of Dual-Cavitation Jet Nozzles: Flow Dynamics and Sandstone Breakage Performance

Due to its high erosion efficiency and energy utilization efficiency, cavitation jet technology demonstrates broad application prospects in energy development fields such as oil and gas well drilling, reservoir stimulation, wellbore cleaning, and rock breaking. Dual-cavitation jet technology significantly enhances cavitation erosion performance by coupling two cavitation-inducing structures within the same nozzle. Based on this technology and considering geometric structural factors, three types of dual-cavitation nozzles are designed in this study: the angular–organ pipe cavitation jet nozzle (AOPCJN), the dual Helmholtz cavitation jet nozzle (DHCJN), and the angular–Helmholtz cavitation jet nozzle (AHCJN). Numerical simulations are conducted to investigate their flow field characteristics, while laboratory experiments are performed to evaluate their rock-breaking performance. The results show that AOPCJN exhibits continuous jet rock-breaking characteristics, whereas DHCJN and AHCJN exhibit pulsating jet characteristics. Under conditions of an injection pressure of 20 MPa, a confining pressure of 0.1 MPa, and a stand-off distance of 10d, AHCJN exhibits the best jet performance, characterized by the longest potential core, a peak wall pulse pressure approaching 20 MPa, a pulse amplitude of 6.88 MPa, and a pulse frequency of 2105 Hz, while its cavitation region can extend directly to the wall surface. In rock-breaking experiments conducted under the same conditions, AHCJN also demonstrates the best performance, producing a hole diameter of 15.03 mm, a depth of 45.58 mm, and an erosion mass of 18.33 g, with a relatively regular hole morphology. The results of this study provide a theoretical basis for the structural optimization of dual-cavitation jet nozzles.