Abrasive water jet is a method with broad application prospects in offshore mineral resource mining. To improve the rock-breaking ability of submerged abrasive water jet (SAWJ), experiments of SAWJ wrapped by annular air jet were carried out. The erosive ability under different ventilation conditions and different dimensionless standoff distances (x/d) was studied by evaluating the area, depth, and volume loss of the eroded sandstone, and the feasibility of this method was verified from the perspective of specific energy consumption. The study found that the sheath can improve the erosion ability of SAWJ under the same working conditions. The rock-breaking effect is better when the ventilation coefficient <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$QS=0.126$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>Q</mi> <mi>S</mi> <mo>=</mo> <mn>0.126</mn> </mrow> </math></EquationSource> </InlineEquation> at <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$x/d=10$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo stretchy="false">/</mo> <mi>d</mi> <mo>=</mo> <mn>10</mn> </mrow> </math></EquationSource> </InlineEquation>, and the maximum area loss of sandstone increases by 31.67%. Compared with traditional SAWJ, this method reduces energy dissipation by 54.01% at <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$x/d<25$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo stretchy="false">/</mo> <mi>d</mi> <mo><</mo> <mn>25</mn> </mrow> </math></EquationSource> </InlineEquation>. The similar flow field evolution trends of submerged water jet and SAWJ were captured by a dynamic image processing method, which assisted in analyzing the role of flow structure in the rock-breaking process. The results show that the entrainment effect makes the jet instability and energy loss caused by the collapse of the air sheath reduce the rock-breaking ability of the jet after exceeding the critical range of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$x/d<20$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo stretchy="false">/</mo> <mi>d</mi> <mo><</mo> <mn>20</mn> </mrow> </math></EquationSource> </InlineEquation>. In addition, the role of cavitation erosion was explored by observing the AL1060 erosion experiment under laser confocal microscopy. The pressure distribution during the erosion process was studied with the model of fluid dynamic impact pressure on the AL1060 surface. The results show that although the contribution of cavitation to surface damage cannot be ignored, the erosive effect of abrasive particles is the main role in aggravating erosion. The interaction between cavitation, abrasive particles and the air sheath significantly changes the erosion dynamics in the SAWJ system. The research results provide insights for optimizing SAWJ parameters, improving rock-breaking ability and understanding the factors affecting erosion behavior.

Experimental Study on Rock-Breaking Mechanism of Submerged Abrasive Jet Assisted by an Air Sheath

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发表日期：

2025年7月25日

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Xiaotian Wang,
Zhaolong Ge,
Wenchuan Liu,
Rongzheng Ge,
Mengting Wang,
Binbin Ge

摘要

Abrasive water jet is a method with broad application prospects in offshore mineral resource mining. To improve the rock-breaking ability of submerged abrasive water jet (SAWJ), experiments of SAWJ wrapped by annular air jet were carried out. The erosive ability under different ventilation conditions and different dimensionless standoff distances (x/d) was studied by evaluating the area, depth, and volume loss of the eroded sandstone, and the feasibility of this method was verified from the perspective of specific energy consumption. The study found that the sheath can improve the erosion ability of SAWJ under the same working conditions. The rock-breaking effect is better when the ventilation coefficient $QS=0.126$ $Q S = 0.126$ at $x/d=10$ $x / d = 10$ , and the maximum area loss of sandstone increases by 31.67%. Compared with traditional SAWJ, this method reduces energy dissipation by 54.01% at $x/d<25$ $x / d < 25$ . The similar flow field evolution trends of submerged water jet and SAWJ were captured by a dynamic image processing method, which assisted in analyzing the role of flow structure in the rock-breaking process. The results show that the entrainment effect makes the jet instability and energy loss caused by the collapse of the air sheath reduce the rock-breaking ability of the jet after exceeding the critical range of $x/d<20$ $x / d < 20$ . In addition, the role of cavitation erosion was explored by observing the AL1060 erosion experiment under laser confocal microscopy. The pressure distribution during the erosion process was studied with the model of fluid dynamic impact pressure on the AL1060 surface. The results show that although the contribution of cavitation to surface damage cannot be ignored, the erosive effect of abrasive particles is the main role in aggravating erosion. The interaction between cavitation, abrasive particles and the air sheath significantly changes the erosion dynamics in the SAWJ system. The research results provide insights for optimizing SAWJ parameters, improving rock-breaking ability and understanding the factors affecting erosion behavior.