Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied throug...Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.展开更多
Density stratification of LNG （liquefied natural gas） is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is conside...Density stratification of LNG （liquefied natural gas） is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is considered to a promising technique to prevent and eliminate stratification in LNG storage tanks. This study is concerned with the numerical simulation of a jet flow issued into a two-layer density-stratified fluid in a tank and the resultant mixing phenomena. The jet behavior was investigated with the laboratory-based experiment of the authors＇ previous study. A numerical method proposed by the authors is employed for the simulation. The upper and lower fluids are water and a NaCl-water solution, respectively, and the lower fluid is issued vertically upward from a nozzle on the bottom of the tank. The Reynolds number （Re） defined by the jet velocity and the nozzle diameter ranges from 95 to 2,378, and the mass concentration of the NaCl-water solution Co is set at 0.02 and 0.04. The simulation highlights the jet-induced mixing between the upper and lower fluids. It also clarifies the effects of Re and C0 on the height and horizontal spread of the jet.展开更多
In the present investigation, we demonstrate the capabilities of the discontinuous Galerkin spectral element method for high order accuracy computation of gas dynamics. The internal flow field of a natural gas injecto...In the present investigation, we demonstrate the capabilities of the discontinuous Galerkin spectral element method for high order accuracy computation of gas dynamics. The internal flow field of a natural gas injector for bivalent combustion engines is investigated under its operating conditions. The simulations of the flow field and the aeroacoustic noise emissions were in a good agreement with the cxperirnental data. We tested several shockcapturing techniques for the discontinuous Galerkin scheme. Based on the validated framework, we analyzed the development of the supersonic jets during different opening procedures of a compressed natural gas injector. The results suggest that a more gradual injector opening decreases the noise emission.展开更多
Y99-61854-336 2003380基于计算机系统的工程学提高课程:建议的课程规划=Engineering of computer-based systems enhancementcourses-proposed course outlines[会,英]/Lavi,J.Z.&Gonzales.R.M.//1999 IEEE Conference and Work-sh...Y99-61854-336 2003380基于计算机系统的工程学提高课程:建议的课程规划=Engineering of computer-based systems enhancementcourses-proposed course outlines[会,英]/Lavi,J.Z.&Gonzales.R.M.//1999 IEEE Conference and Work-shop on Engineering of Computer-Based System.—336343(Fs,U)介绍了系统工程师在系统开发过程中应掌握基于计算机系统的工程学(ECBS)的知识,应该理解的基于计算机系统(CBS)概念,以及在扩充知识时应学习的ECBS 课程的设置。所建议的课程规划可作为本科生或研究生的课程,也可作为企业的培训教程。参202003381电子喷射天然气发动机监控系统的设计[刊]/王贞立//电子工程师.—1999,(11).—40～41(A)展开更多
基金Supported by the National Natural Science Foundation of China(50604019)the Innovation Team Foundation of China(50621403)
文摘Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.
文摘Density stratification of LNG （liquefied natural gas） is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is considered to a promising technique to prevent and eliminate stratification in LNG storage tanks. This study is concerned with the numerical simulation of a jet flow issued into a two-layer density-stratified fluid in a tank and the resultant mixing phenomena. The jet behavior was investigated with the laboratory-based experiment of the authors＇ previous study. A numerical method proposed by the authors is employed for the simulation. The upper and lower fluids are water and a NaCl-water solution, respectively, and the lower fluid is issued vertically upward from a nozzle on the bottom of the tank. The Reynolds number （Re） defined by the jet velocity and the nozzle diameter ranges from 95 to 2,378, and the mass concentration of the NaCl-water solution Co is set at 0.02 and 0.04. The simulation highlights the jet-induced mixing between the upper and lower fluids. It also clarifies the effects of Re and C0 on the height and horizontal spread of the jet.
基金supported by the Bundesministerium fur Bildung und Forschung(BMBF)in the context of the HONK Project
文摘In the present investigation, we demonstrate the capabilities of the discontinuous Galerkin spectral element method for high order accuracy computation of gas dynamics. The internal flow field of a natural gas injector for bivalent combustion engines is investigated under its operating conditions. The simulations of the flow field and the aeroacoustic noise emissions were in a good agreement with the cxperirnental data. We tested several shockcapturing techniques for the discontinuous Galerkin scheme. Based on the validated framework, we analyzed the development of the supersonic jets during different opening procedures of a compressed natural gas injector. The results suggest that a more gradual injector opening decreases the noise emission.
文摘Y99-61854-336 2003380基于计算机系统的工程学提高课程:建议的课程规划=Engineering of computer-based systems enhancementcourses-proposed course outlines[会,英]/Lavi,J.Z.&Gonzales.R.M.//1999 IEEE Conference and Work-shop on Engineering of Computer-Based System.—336343(Fs,U)介绍了系统工程师在系统开发过程中应掌握基于计算机系统的工程学(ECBS)的知识,应该理解的基于计算机系统(CBS)概念,以及在扩充知识时应学习的ECBS 课程的设置。所建议的课程规划可作为本科生或研究生的课程,也可作为企业的培训教程。参202003381电子喷射天然气发动机监控系统的设计[刊]/王贞立//电子工程师.—1999,(11).—40～41(A)
