Optimization of high-pressure air jet parameters and analysis of erosion characteristics for similar materials in coal bodies

In order to effectively avoid the possible drawbacks of water seal inhibiting gas resolution and reducing coal seam permeability, based on the existing air jet research foundation, theoretical analysis and laboratory experiments were used to analyze and study the punching characteristics of high-pressure air jets and the law of punching and breaking coal under the combination of jet parameters. The results show that, among the three factors affecting the experimental results, the jet pressure has the greatest influence, the impact target distance is second, and the nozzle size has the least influence on the experimental results; the optimal combination of jet parameters in the experimental range is 12 MPa, 30 mm impact target distance and 3.5 Mach number nozzle size. The effect of jet punching increases with the increase of jet pressure, when the jet pressure reaches 10 MPa, the specimen penetrates, and when it is further increased to 12 MPa, the specimen is broken; there is an optimal impact target distance for jet punching, and the jet punching effect is the best under this target distance, which is generally 6-7 times the nozzle diameter; the nozzle size has little effect on the effect of punching experiments, and the punching effect tends to be constant.