Supercritical carbon dioxide(Sc-CO_(2))jet rock breaking is a nonlinear impact dynamics problem involving many factors.Considering the complexity of the physical properties of the Sc-CO_(2)jet and the mesh distortion ...Supercritical carbon dioxide(Sc-CO_(2))jet rock breaking is a nonlinear impact dynamics problem involving many factors.Considering the complexity of the physical properties of the Sc-CO_(2)jet and the mesh distortion problem in dealing with large deformation problems using the finite element method,the smoothed particle hydrodynamics(SPH)method is used to simulate and analyze the rock breaking process by Sc-CO_(2)jet based on the derivation of the jet velocity-density evolution mathematical model.The results indicate that there exists an optimal rock breaking temperature by Sc-CO_(2).The volume and length of the rock fracture increase with the rising of the jet temperature but falls when the jet temperature exceeds 340 K.With more complicated perforation shapes and larger fracture volumes,the Sc-CO_(2)jet can yield a rock breaking more effectively than water jet,The stress analysis shows that the Sc-CO_(2)rock fracturing process could be reasonably divided into three stages,namely the fracture accumulation stage,the rapid failure stage,and the breaking stabilization stage.The high diffusivity of Sc-CO_(2)is identified as the primary cause of the stress fluctuation and W-shaped fracture morphology.The simulated and calculated results are generally in conformity with the published experimental data.This study provides theoretical guidance for further study on Sc-CO_(2)fracturing mechanism and rock breaking efficiency.展开更多
The supercritical carbon dioxide （SC-CO2） jet can break rocks at higher penetration rates and lower threshold pressures than the water jet. The abrasive SC-CO2 jet, formed by adding solid particles into the SC-CO2 j...The supercritical carbon dioxide （SC-CO2） jet can break rocks at higher penetration rates and lower threshold pressures than the water jet. The abrasive SC-CO2 jet, formed by adding solid particles into the SC-CO2 jet, is expected to achieve higher operation efficiency in eroding hard rocks and cutting metals. With the computational fluid dynamics numerical simulation method, the characteristics of the flow field of the abrasive SC-CO2 jet are analyzed, as well as the main influencing factors. Results show that the two-phase axial velocities of the abrasive SC-CO2 jet is much higher than those of the abrasive water jet, when the pressure difference across the jet nozzle is held constant at 20 MPa, the optimal standoff distance for the largest particle impact velocity is approximately 5 times of the jet nozzle diameter; the fluid temperature and the volume concentration of the abrasive particles have modest influences on the two-phase velocities, the ambient pressure has a negligible influence when the pressure difference is held constant. Therefore the abrasive SC-CO2 jet is expected to assure more effective erosion and cutting performance. This work can provide guidance for subsequent lab experiments and promote practical applications.展开更多
基金National Natural Science Foundation of China,Nos.51674267,51874310.
文摘Supercritical carbon dioxide(Sc-CO_(2))jet rock breaking is a nonlinear impact dynamics problem involving many factors.Considering the complexity of the physical properties of the Sc-CO_(2)jet and the mesh distortion problem in dealing with large deformation problems using the finite element method,the smoothed particle hydrodynamics(SPH)method is used to simulate and analyze the rock breaking process by Sc-CO_(2)jet based on the derivation of the jet velocity-density evolution mathematical model.The results indicate that there exists an optimal rock breaking temperature by Sc-CO_(2).The volume and length of the rock fracture increase with the rising of the jet temperature but falls when the jet temperature exceeds 340 K.With more complicated perforation shapes and larger fracture volumes,the Sc-CO_(2)jet can yield a rock breaking more effectively than water jet,The stress analysis shows that the Sc-CO_(2)rock fracturing process could be reasonably divided into three stages,namely the fracture accumulation stage,the rapid failure stage,and the breaking stabilization stage.The high diffusivity of Sc-CO_(2)is identified as the primary cause of the stress fluctuation and W-shaped fracture morphology.The simulated and calculated results are generally in conformity with the published experimental data.This study provides theoretical guidance for further study on Sc-CO_(2)fracturing mechanism and rock breaking efficiency.
基金supported by the National Natural Science Foundation of China(Grant No.51304226)the National Key Basic Research Development Program of China(973 Program,Grant No.2014CB239203)
文摘The supercritical carbon dioxide （SC-CO2） jet can break rocks at higher penetration rates and lower threshold pressures than the water jet. The abrasive SC-CO2 jet, formed by adding solid particles into the SC-CO2 jet, is expected to achieve higher operation efficiency in eroding hard rocks and cutting metals. With the computational fluid dynamics numerical simulation method, the characteristics of the flow field of the abrasive SC-CO2 jet are analyzed, as well as the main influencing factors. Results show that the two-phase axial velocities of the abrasive SC-CO2 jet is much higher than those of the abrasive water jet, when the pressure difference across the jet nozzle is held constant at 20 MPa, the optimal standoff distance for the largest particle impact velocity is approximately 5 times of the jet nozzle diameter; the fluid temperature and the volume concentration of the abrasive particles have modest influences on the two-phase velocities, the ambient pressure has a negligible influence when the pressure difference is held constant. Therefore the abrasive SC-CO2 jet is expected to assure more effective erosion and cutting performance. This work can provide guidance for subsequent lab experiments and promote practical applications.
