Numerical Simulation and Experimental Study on High-Pressure Water Jet Descaling in Coal Mine Drainage Pipeline

Abstract

Traditional chemical and mechanical descaling methods are expensive, inefficient and environmental pollution for removing scales in coal mine main drainage pipeline. In this study, a water jet is proposed to remove pipe scales, which can solve the inadequacies of traditional methods. Parametric optimization for water jet and descaling nozzle are analyzed. Firstly, the mechanical properties of scale materials are obtained for the first time by uniaxial compressive tests and Brazilian disk splitting tests. Secondly, crushing mechanism and crushing effect of pipe scale subjected to water jet are studied by AUTODYN software. Relationship between the nozzle’s key structure parameters and the axial static pressure and velocity of the fluid field inside the nozzle are analyzed by Fluent software. Moreover, the axial dynamic pressure and velocity of fluid field outside the nozzle are also analyzed. The above numerical simulations indicate that the pressure, flow and target distance of water jet should be 20 MPa, 40L/min and 50 mm, respectively; the outlet diameter, contraction angle and length-diameter ratio of the nozzle should be 2 mm, 13°and 2, respectively. Finally, experiments are conducted for the validation of these parameters. The results provide guidance for the development of the water jet descaling technique of the coal mine drainage pipeline.