In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling &hydraulic impact hard-rock tunneling(DHIHT) technology and method. Based on the LS-DYNA explicit module...In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling &hydraulic impact hard-rock tunneling(DHIHT) technology and method. Based on the LS-DYNA explicit module and APDL programming, the key parameters of DHIHT, including drilling spacing and drilling radius, were investigated. The simulation results show that: the drilling spacing should not exceed0.20 m-larger distances weaken the actual breaking effect; the best drilling radius is about 0.035 m, larger or smaller distances would both decrease the effect of drilling-hole free surfaces. The field impact breaking experiments were conducted in Baitaizi township granite quarry, Jinzhou, Liaoning province,China. The experiment results indicate that DHIHT is a feasible method for hard-rock tunneling, but its efficiency still needs to be further optimized and improved.展开更多
To evaluate the quality and damage condition of the electrolyzer,wave velocity detection technology and impact echo technology were used to detect the cathode part of the electrolyzer.The experimental results show tha...To evaluate the quality and damage condition of the electrolyzer,wave velocity detection technology and impact echo technology were used to detect the cathode part of the electrolyzer.The experimental results show that wave velocity is linearly related to the porosity,and there is also a linear relationship between wave velocity and the square root of reciprocal density in cathode carbon blocks(CCBs)before installation into electrolyzer.Combined with detection results of wave velocity and voltage drop,the large-size CCBs with relatively good quality can be found.Through the impact echo technology on cathode steel rods(CSRs),the results of the on-site detection show that the damage condition of CSRs can be effectively evaluated,and the damage location of CSRs can be determined.This study proposes a novel and quantifiable method for the evaluation of cathode quality and damage,which provides a reference for prolonging the service life of the electrolyzer.展开更多
Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure...Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure distribution,the liquid diameter distribution,and the liquid velocity distribution.With a sufficient mesh resolution,the liquid morphology can be captured in a physically sound way.A mushroom tip is triggered by a larger radial jet velocity and breakup happens at the tip edge first.Different kinds of ligament breakup patterns due to aerodynamic force and surface tension are captured on the axial sheet.A high pressure core is spotted at the impinging point region.A larger radial jet velocity can feed more disturbances into the impinging point and the axial sheet,generate stronger vortices to promote the breakup process at a longer distance,and form a larger spray half cone angle.Because of the re-collision phenomenon the axial sheet diameter does not decrease monotonically.The inner rim on the axial sheet shows a larger diameter magnitude and a lower velocity magnitude due to surface tension.This paper is expected to provide a reference for the optimum design of a liquid-liquid pintle injector.展开更多
基金supported by the Staring Project of Youth Team of Taiyuan University of Technology (No. 2013T036)the Qualified Personnel Foundation of Taiyuan University of Technology (No. TYUT-RC201426a)the 2014 Shanxi Coal-based Key Scientific & Technological Project (No. MJ2014-06)
文摘In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling &hydraulic impact hard-rock tunneling(DHIHT) technology and method. Based on the LS-DYNA explicit module and APDL programming, the key parameters of DHIHT, including drilling spacing and drilling radius, were investigated. The simulation results show that: the drilling spacing should not exceed0.20 m-larger distances weaken the actual breaking effect; the best drilling radius is about 0.035 m, larger or smaller distances would both decrease the effect of drilling-hole free surfaces. The field impact breaking experiments were conducted in Baitaizi township granite quarry, Jinzhou, Liaoning province,China. The experiment results indicate that DHIHT is a feasible method for hard-rock tunneling, but its efficiency still needs to be further optimized and improved.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.42172316)the Natural Science Foundation of Hunan Province,China(No.2021JJ30810)the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining,China(No.CUMT SKLCRSM21KF005).
文摘To evaluate the quality and damage condition of the electrolyzer,wave velocity detection technology and impact echo technology were used to detect the cathode part of the electrolyzer.The experimental results show that wave velocity is linearly related to the porosity,and there is also a linear relationship between wave velocity and the square root of reciprocal density in cathode carbon blocks(CCBs)before installation into electrolyzer.Combined with detection results of wave velocity and voltage drop,the large-size CCBs with relatively good quality can be found.Through the impact echo technology on cathode steel rods(CSRs),the results of the on-site detection show that the damage condition of CSRs can be effectively evaluated,and the damage location of CSRs can be determined.This study proposes a novel and quantifiable method for the evaluation of cathode quality and damage,which provides a reference for prolonging the service life of the electrolyzer.
基金supported by the National Natural Science Foundation of China(No.11572346)。
文摘Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure distribution,the liquid diameter distribution,and the liquid velocity distribution.With a sufficient mesh resolution,the liquid morphology can be captured in a physically sound way.A mushroom tip is triggered by a larger radial jet velocity and breakup happens at the tip edge first.Different kinds of ligament breakup patterns due to aerodynamic force and surface tension are captured on the axial sheet.A high pressure core is spotted at the impinging point region.A larger radial jet velocity can feed more disturbances into the impinging point and the axial sheet,generate stronger vortices to promote the breakup process at a longer distance,and form a larger spray half cone angle.Because of the re-collision phenomenon the axial sheet diameter does not decrease monotonically.The inner rim on the axial sheet shows a larger diameter magnitude and a lower velocity magnitude due to surface tension.This paper is expected to provide a reference for the optimum design of a liquid-liquid pintle injector.
