Abstract

Cutting and breaking operations are common in underwater drilling and mining engineering. Because the resistance of the underwater environment is reduced, the gas-assisted water jet method improves the rock-breaking performance of ordinary water jets. However, the rock-breaking mechanism of a gas–liquid two-phase jet in an underwater environment is unclear. Furthermore, the influence of the jet parameters on its rock-breaking performance needs to be studied. Therefore, the fundamental structure of an underwater gas–liquid two-phase jet was analyzed further in this work. On this basis, a rock-breaking orthogonal experiment was conducted. The effects of the water jet system pressure, air flow pressure, transverse velocity, and erosion distance on the rock-breaking performance of underwater gas–liquid two-phase jet were investigated. The essential reasons for the variation in jet erosion performance were discussed. Furthermore, the order of importance and significance of the above four factors on the rock-breaking performance were analyzed, and reasonable jet working parameters were determined. The results show that rock breaking is the result of the joint action of the microjet formed by the water-phase jet impact and gas-phase cavitation collapse. In general, the system pressure has the highest impact on the rock-breaking performance. Therefore, a higher water-jet system pressure should be applied in underwater gas–liquid two-phase jet-breaking operations. The preferred values of the working parameters for the test conditions and selected parameters are as follows: air flow pressure = 0.4 MPa, traverse velocity = 3 m/min, and erosion distance = 10 mm. The research results can provide technical guidance and a reference for underwater cutting and breaking operations.

摘要

切割和破碎操作在水下钻井和采矿工程中很常见。由于降低了水下环境的阻力，气体辅助水射流法提高了普通水射流的破岩性能。然而，气液两相射流在水下环境中的破岩机制尚不清楚。此外，射流参数对其破岩性能的影响还有待研究。因此，本文进一步分析了水下气液两相射流的基本结构。在此基础上，进行了破岩正交试验。研究了水射流系统压力、气流压力、横向速度和冲蚀距离对水下气液两相射流破岩性能的影响。讨论了射流侵蚀性能变化的本质原因。进一步分析了上述4个因素对破岩性能的重要性和重要性的排序，确定了合理的射流工作参数。结果表明，破岩是水相射流冲击和气相空化坍塌形成的微射流共同作用的结果。一般来说，系统压力对破岩性能的影响最大。因此，水下气液两相射流破断作业应采用较高的水射流系统压力。试验条件和选定参数的工作参数优选值如下：气流压力 = 0.4 MPa，横向速度 = 3 m/min，冲蚀距离 = 10 mm。