The objective of the present investigation is to analyze the influence of profile of blast furnace on the burden motion and stress field through 3D-DEM （three-dimensional discrete element method）. It is clarified th...The objective of the present investigation is to analyze the influence of profile of blast furnace on the burden motion and stress field through 3D-DEM （three-dimensional discrete element method）. It is clarified that the decrease of shaft angle speeds up the velocity of burden descending and decreases normal stress between particles or particle and wall. This change is good for the smooth operation of blast furnace. However, ore and coke would be mixed for the too small shaft angle （75~） , which would influence the permeability in blast furnace. Thus, the appro- priate shaft angle is around 80°. Decrease of bosh angle prevents the burden descending motion and increases normal stress between particles and bosh wall. Meanwhile, maximum normal stress acting on the wall moves from belly wall to bosh wall in the case of 68° bosh angle, which accelerates abrasion of refractory in bosh by friction force between particles and wall. Although burden descends smoothly in the case of 88° bosh angle, room is not enough for the as- cending heated gas flow. Thus, the appropriate bosh angle is about 78°.展开更多
Features of the motion of gel particles in a three-phase bubble column with non-foaming and foaming gas–liquid systems,determined by using experiments of radioactive particle tracking(RPT),have been compared.The trac...Features of the motion of gel particles in a three-phase bubble column with non-foaming and foaming gas–liquid systems,determined by using experiments of radioactive particle tracking(RPT),have been compared.The tracer used is a gel particle which resembles typical immobilized biocatalyst.The tracer trajectory is analyzed to extract relevant information for design purposes.The solid velocity field,turbulence parameters,dispersion coefficients,mixing times and flow transitions are determined and compared.The presence of foam significantly affects many quantified parameters,especially within the heterogeneous flow regime.The hydrodynamic stresses are reduced in the presence of foam,especially close to the disengagement.The dispersion coefficients also decrease,and the solid mixing time is only slightly affected by the presence of foam.Gas holdup,inferred both from RPT experiments and from gamma ray scanning,is higher for foaming systems and leads to a shift in the transition gas velocity towards higher values.展开更多
Solid contamination existing as solid particles in power fluid transmission systems may lead to transmission performance reduction,system failures,and component damage.The hydraulic reservoir will deposit the contamin...Solid contamination existing as solid particles in power fluid transmission systems may lead to transmission performance reduction,system failures,and component damage.The hydraulic reservoir will deposit the contamination and store hydraulic fluid.To investigate its purification ability for solid contamination,experiments and simulations for the motion and deposition status of the typical hydraulic system particles are carried out to reveal the interaction of particles and fluid in hydraulic water reservoirs.The results show that the CFD-DEM coupling method could predict the accurate deposition position of iron particles and sand particles when ignoring the small-scale turbulence effect in the flow field.Besides,the particle motion traces and deposition patterns in the reservoir illustrate that the flow development on the bottom surface results in the particles turning,and particles tend to settle in the low flow energy position.The motion of particles is also linked to particles Stokes number,and the same-size sand particles are easily driven by the fluid.The contribution of this paper could provide a guide for predicting the particle motion and deposition pattern in the hydraulic reservoir.展开更多
By means of Solid Works, three-dimensional model of automated assembly system was established, and kinematic simulation based on Solid Works Motion of assembly process for relay was performed. The simulation results p...By means of Solid Works, three-dimensional model of automated assembly system was established, and kinematic simulation based on Solid Works Motion of assembly process for relay was performed. The simulation results proved the feasibility of mechanical design. Eventually, the productivity was estimated based on simulation analysis. The mechanical design provided a solution with high reference value to practical design of automated assembly system for relay.展开更多
Molecular motion in the solid-state is an important yet underexplored natural phenomenon.The discovery of unconventional molecular motion in the solid-state is of considerable scientific interest and could potentially...Molecular motion in the solid-state is an important yet underexplored natural phenomenon.The discovery of unconventional molecular motion in the solid-state is of considerable scientific interest and could potentially facilitate the development of novel functional materials[1].In contrast to the situation in solution,where molecular motion is generally free and easily controlled,the high viscosity and dense packing characteristic of most solid-state substances make molecular movement and its controlled induction particularly challenging.展开更多
文摘The objective of the present investigation is to analyze the influence of profile of blast furnace on the burden motion and stress field through 3D-DEM （three-dimensional discrete element method）. It is clarified that the decrease of shaft angle speeds up the velocity of burden descending and decreases normal stress between particles or particle and wall. This change is good for the smooth operation of blast furnace. However, ore and coke would be mixed for the too small shaft angle （75~） , which would influence the permeability in blast furnace. Thus, the appro- priate shaft angle is around 80°. Decrease of bosh angle prevents the burden descending motion and increases normal stress between particles and bosh wall. Meanwhile, maximum normal stress acting on the wall moves from belly wall to bosh wall in the case of 68° bosh angle, which accelerates abrasion of refractory in bosh by friction force between particles and wall. Although burden descends smoothly in the case of 88° bosh angle, room is not enough for the as- cending heated gas flow. Thus, the appropriate bosh angle is about 78°.
基金Supported by the FONCyT(PICT2014-0704)CONICET(PIP1122015-0100902CO)Universidad de Buenos Aires(UBACyT 20020130100544BA)
文摘Features of the motion of gel particles in a three-phase bubble column with non-foaming and foaming gas–liquid systems,determined by using experiments of radioactive particle tracking(RPT),have been compared.The tracer used is a gel particle which resembles typical immobilized biocatalyst.The tracer trajectory is analyzed to extract relevant information for design purposes.The solid velocity field,turbulence parameters,dispersion coefficients,mixing times and flow transitions are determined and compared.The presence of foam significantly affects many quantified parameters,especially within the heterogeneous flow regime.The hydrodynamic stresses are reduced in the presence of foam,especially close to the disengagement.The dispersion coefficients also decrease,and the solid mixing time is only slightly affected by the presence of foam.Gas holdup,inferred both from RPT experiments and from gamma ray scanning,is higher for foaming systems and leads to a shift in the transition gas velocity towards higher values.
基金National Key Research and Development Program of China(Grant No.2018YFB2000703)National Natural Science Foundation of China(Grant No.51975507).
文摘Solid contamination existing as solid particles in power fluid transmission systems may lead to transmission performance reduction,system failures,and component damage.The hydraulic reservoir will deposit the contamination and store hydraulic fluid.To investigate its purification ability for solid contamination,experiments and simulations for the motion and deposition status of the typical hydraulic system particles are carried out to reveal the interaction of particles and fluid in hydraulic water reservoirs.The results show that the CFD-DEM coupling method could predict the accurate deposition position of iron particles and sand particles when ignoring the small-scale turbulence effect in the flow field.Besides,the particle motion traces and deposition patterns in the reservoir illustrate that the flow development on the bottom surface results in the particles turning,and particles tend to settle in the low flow energy position.The motion of particles is also linked to particles Stokes number,and the same-size sand particles are easily driven by the fluid.The contribution of this paper could provide a guide for predicting the particle motion and deposition pattern in the hydraulic reservoir.
文摘By means of Solid Works, three-dimensional model of automated assembly system was established, and kinematic simulation based on Solid Works Motion of assembly process for relay was performed. The simulation results proved the feasibility of mechanical design. Eventually, the productivity was estimated based on simulation analysis. The mechanical design provided a solution with high reference value to practical design of automated assembly system for relay.
基金supported by the National Natural Science Foundation of China(22271090)。
文摘Molecular motion in the solid-state is an important yet underexplored natural phenomenon.The discovery of unconventional molecular motion in the solid-state is of considerable scientific interest and could potentially facilitate the development of novel functional materials[1].In contrast to the situation in solution,where molecular motion is generally free and easily controlled,the high viscosity and dense packing characteristic of most solid-state substances make molecular movement and its controlled induction particularly challenging.
