Abstract:
As coal mining extends deeper, pure water jet technology is gradually unable to meet the demand for coal penetration enhancement under high stress and high coal rock strength conditions. Abrasive water jet can effectively improve the rock breaking ability of water jet, and the abrasive water jet rotary cutting pressure relief technology can achieve efficient anti permeability of high stress and hard coal seams. Jet pressure and rotation speed are important factors affecting the effectiveness of abrasive water jet rotary cutting of coal and rock. Clarifying the mechanical characteristics and laws of abrasive water jet rotary cutting of hard coal is a prerequisite for reasonably matching jet pressure and rotation speed. This article adopts a combination of numerical simulation and experimental research to analyze the influence of different jet pressure and rotation speed matching relationships on the mechanical mechanism of jet impact on the target body, and clarify the influence rules of different jet pressure and rotation speed on the cutting effect of abrasive water jet rotation. The research results indicate that the normal force generated by the high-speed impact of abrasive particles on coal and rock mainly depends on the jet pressure, while the tangential force depends on both the jet pressure and the rotational speed. The normal force and tangential force have different effects on the impact of abrasive particles on coal breaking, and together determine the effect of abrasive water jet rotation cutting coal and rock. When the jet pressure is less than 25 MPa, the cutting depth increases with the increase of jet pressure, and the rate of increase in cutting depth significantly decreases after exceeding 25 MPa. Under the condition of constant cutting time, the cutting depth of abrasive jet rotation always shows an upward trend with the increase of rotation speed. Propose to use the optimal matching coefficient
n as the evaluation index for cutting effects at different speeds under the same jet pressure. It was found that there were significant differences in the value of
n between submerged and non submerged conditions under different working conditions. The optimal parameter matching coefficient
n for non submerged conditions is
0.0020156, while for submerged conditions it is
0.000299. A calculation model for the optimal matching parameters of abrasive water jet rotating slotting jet pressure and rotation speed has been established. The optimal matching speed can be directly calculated based on the jet pressure, resulting in the best jet cutting effect.