To improve the rock breaking ability, cavitating waterjet and abrasive waterjet are combined by using a coaxial low-speed waterjet generated around the periphery of a high-speed abrasive waterjet, and a new type of waterjet called unsubmerged cavitating abrasive waterjet (UCAWJ) is thus produced. The rock breaking performance of UCAWJ was compared with submerged cavitating abrasive waterjet (SCAWJ) and unsubmerged abrasive waterjet (UAWJ) by impinging sandstone specimens. Moreover, the effects of jet pressure, standoff distance, abrasive flow rate and concentration were studied by evaluating the specific energy consumption, and the area, depth, and mass loss of the eroded specimen. The results show that the artificially generated submerged environment in UCAWJ is able to enhance the rock breaking performance under the same operating parameters. Furthermore, the rock breaking performance of UCAWJ is much better at higher jet pressures and smaller standoff distances when compared with UAWJ. The greatest rock breaking ability of UCAWJ appears at jet pressure of 50 MPa and standoff distance of 32 mm, with the mass loss of sandstone increased by 370.6% and the energy dissipation decreased by 75.8%. In addition, under the experimental conditions the optimal abrasive flow rate and concentration are 76.5 mL/min and 3%, respectively.

为了提高破岩能力，利用高速磨料水射流周围产生的同轴低速水射流将空化水射流和磨料水射流结合起来，形成了一种新型水射流，称为非浸没式空化磨料水射流（UCAWJ）。产生的。通过冲击砂岩样本，将 UCAWJ 与浸没式磨料水射流 (SCAWJ) 和非浸没式磨料水射流 (UAWJ) 的破岩性能进行比较。此外，通过评估特定能量消耗以及侵蚀样本的面积、深度和质量损失，研究了射流压力、间隔距离、磨料流量和浓度的影响。结果表明，在相同作业参数下，UCAWJ人工生成的水下环境能够提高破岩性能。此外，与 UAWJ 相比，UCAWJ 在较高射流压力和较小隔离距离下的破岩性能要好得多。UCAWJ在射流压力为50 MPa、射流距离为32 mm时具有最大破岩能力，砂岩质量损失增加370.6%，能量耗散减少75.8%。此外，在实验条件下，最佳磨料流量和浓度分别为76.5 mL/min和3%。