Research on inclined impact characteristics of circular nozzle water jet
Zhang Yongbin
Abstract：Most coal seams in China have the characteristics of micropores,low permeability,and high adsorption,and hydraulic punc-hing is one of the methods to improve their permeability.The optimal parameters of coal breaking and permeability increasing nozzle can be obtained by studying the characteristics of inclined impact of circular nozzle water jet on coal and rock breaking.Using numerical simulation software COMSOL Multiphysics,a 3D model of circular nozzle impact drilling was established to study the jet impact charac-teristics of circular nozzle under different inclination angles(30 °-90 °),impact velocities(300-800 m/s),and nozzle diameters(10 mm≤D≤35 mm).The results indicate that as the inclination angle of the jet increases,the maximum pressure value of jet on drilling wall and the water jet velocity reaching the drilling wall shows a trend of first increasing and then decreasing.As the impact velocity gradually increases,the area of coal damage also increases,and as the wall distance gradually increases,the stress decreases,causing less damage to the coal body.The increase in nozzle diameter leads to an increase in water jet flow rate,causing the maximum velocity reaching the borehole wall to gradually increase and the range of jet distribution to gradually expand.
Keywords：water jetinclination angleimpact velocitynozzle diameter
Publication Date：2025-08-25
Online Publishing Date：2025-09-12(First online date of this platform, not the publication date of the document)
Pages：6( 80-85 )