Numerical study on particle-carrying ability of liquid nitrogen jet

Abstract

ABSTRACT Liquid nitrogen (LN2) jet is expected to have the higher rock-breaking efficiency than water jet as its ultra-low temperature characteristic. It is considered that adding a few solid particles into LN2 jet can noticeably enhance its rock-breaking capability. The abrasive LN2 jet has a great application prospect in petroleum as well as geothermal exploitation. This study investigates the particle-carrying ability of LN2 jet by a 3D numerical model. The geometric model adopts a spindle shape that is more similar to the realistic cavity created by abrasive jet. The standard model and discrete phase model are used to calculate the LN2 flow and the particle trajectory, respectively. The Discrete Random Walk model is applied to describe the particle space movement in flow field. The results show that the particle in abrasive LN2 jet obtains the highest nozzle exit velocity in simulation conditions, 11.1% higher than in water jet and 5.1% higher than in SC-CO2 jet. The potential core of abrasive LN2 jet is longest in these three types of abrasive jets. That means LN2 jet has a well particle-carrying ability at high-speed state. However, the LN2 turbulent flow at out-of-nozzle region causes the violent fluctuation of particle speed. Parametric analysis indicates that the nozzle pressure drop and nozzle diameter in LN2 jet have the vital influences on particle velocity, while the ambient pressure and particle diameter affect particle velocity slightly. The simulation results reveal the particle-carrying ability of LN2 jet in different conditions. It would shed light on cutting capability of abrasive LN2 jet and promote its application in petroleum and geothermal exploitation.