Pumped storage power stations on sediment-laden rivers are highly susceptible to erosion damage on the surfaces of major flow-passingcomponents due to sediment particles.In this study,an Euler-Lagrange model is employ...Pumped storage power stations on sediment-laden rivers are highly susceptible to erosion damage on the surfaces of major flow-passingcomponents due to sediment particles.In this study,an Euler-Lagrange model is employed to numerically investigate the sand-water flowcharacteristics and erosion prediction of a pump-turbine under hump-region conditions,focusing on crest,trough,and high-flow operatingpoints.The results show that the internal flow of the pump-turbine undergoes significant changes in the hump region.Under low-flowconditions,flow separation,backflow,and local vortex phenomena occur inside the runner.Vortices in the runner passages tend to entrainsediment particles,resulting in a reduction in particle velocity.With increasing sand-water flow rate,a pronounced velocity difference developson both sides of the blades,with the maximum difference reaching 20 m/s.The average erosion rates on the runner blades and the endfaces of the guide vanes are 4.2×10^(-8) and 3.5×10^(-8) kg/(s·m^(2)),respectively.The cutting erosion patterns on the blade surfaces coincide withthe trajectories of the water flow vortices,and the erosion rate distribution on the guide vane end faces shows a high degree of consistencywith the distribution of sand-water vortices.展开更多
Janus particles,in which two distinct compositions are integrated,have attracted considerable interest for their potential multi-functionalities and synergistic effects.Although seed-mediated growth appears to be a su...Janus particles,in which two distinct compositions are integrated,have attracted considerable interest for their potential multi-functionalities and synergistic effects.Although seed-mediated growth appears to be a suitable strategy that meets the stringent specifications for obtaining Janus particles,it is inapplicable to guide the growth of two crystalline components with different crystal structures.Herein,the formation of Janus particles via phase segregation is proposed.As proof-of-concept,promising photon conversion materials,ScF_(3)and lanthanide(Ln)fluorides,with great differences in structure,were chosen to build a series of Janus particles.Interestingly,using heavy(Lu,Yb,Dy and Tb)and light(Pr,Nd,Sm,Eu and Gd)lanthanides,ScF_(3)-LiLnF_(4)and ScF_(3)-LnF_(3)were formed,respectively.Time-dependent reaction studies indicate that phase segregation paves the way for the formation of these Janus nanoparticles(NPs),and this speculation is further confirmed by in situ transmission electron microscopy observations.These investigations provide new insights for the synthesis of heterostructured materials.展开更多
Traditional tin(Sn)-based oxide materials suffer from huge volume expansion/contraction during discharge/charge cycling,resulting in poor cyclic stability when they are used as anode materials.In comparison,the bimeta...Traditional tin(Sn)-based oxide materials suffer from huge volume expansion/contraction during discharge/charge cycling,resulting in poor cyclic stability when they are used as anode materials.In comparison,the bimetal Sn-based oxides have gained increasing attention in the field of rechargeable sodium ion batteries(SIBs)because of the synergism between the metal components,which prevents agglomeration of the active particles.In this work,the electrochemical performances of copper tin oxide(CuSnO_(3))as an anode material for SIBs were investigated for the first time.展开更多
文摘Pumped storage power stations on sediment-laden rivers are highly susceptible to erosion damage on the surfaces of major flow-passingcomponents due to sediment particles.In this study,an Euler-Lagrange model is employed to numerically investigate the sand-water flowcharacteristics and erosion prediction of a pump-turbine under hump-region conditions,focusing on crest,trough,and high-flow operatingpoints.The results show that the internal flow of the pump-turbine undergoes significant changes in the hump region.Under low-flowconditions,flow separation,backflow,and local vortex phenomena occur inside the runner.Vortices in the runner passages tend to entrainsediment particles,resulting in a reduction in particle velocity.With increasing sand-water flow rate,a pronounced velocity difference developson both sides of the blades,with the maximum difference reaching 20 m/s.The average erosion rates on the runner blades and the endfaces of the guide vanes are 4.2×10^(-8) and 3.5×10^(-8) kg/(s·m^(2)),respectively.The cutting erosion patterns on the blade surfaces coincide withthe trajectories of the water flow vortices,and the erosion rate distribution on the guide vane end faces shows a high degree of consistencywith the distribution of sand-water vortices.
基金supported by NSFC(No.21425101,21371011,21331001,21590791)MOST of China(2014CB643800,2017YFA0205101).
文摘Janus particles,in which two distinct compositions are integrated,have attracted considerable interest for their potential multi-functionalities and synergistic effects.Although seed-mediated growth appears to be a suitable strategy that meets the stringent specifications for obtaining Janus particles,it is inapplicable to guide the growth of two crystalline components with different crystal structures.Herein,the formation of Janus particles via phase segregation is proposed.As proof-of-concept,promising photon conversion materials,ScF_(3)and lanthanide(Ln)fluorides,with great differences in structure,were chosen to build a series of Janus particles.Interestingly,using heavy(Lu,Yb,Dy and Tb)and light(Pr,Nd,Sm,Eu and Gd)lanthanides,ScF_(3)-LiLnF_(4)and ScF_(3)-LnF_(3)were formed,respectively.Time-dependent reaction studies indicate that phase segregation paves the way for the formation of these Janus nanoparticles(NPs),and this speculation is further confirmed by in situ transmission electron microscopy observations.These investigations provide new insights for the synthesis of heterostructured materials.
基金supported by the National Key Research and Development Program of China(2016YFA0202601,2016YFA0202603)the National Natural Science Foundation of China(51521001,51602239)+2 种基金the Programme of Introducing Talents of Discipline to Universities(B17034)the International Science&Technology Cooperation Program of China(2013DFA50840)the Yellow Crane Talent(Science&Technology)Program of Wuhan City and the Fundamental Research Funds for the Central Universities(WUT:2017III009,2017III005).We are grateful to Yun Liang,the Ningbo Institute of Materials Technology and Engineering for drawing the graphics.
文摘Traditional tin(Sn)-based oxide materials suffer from huge volume expansion/contraction during discharge/charge cycling,resulting in poor cyclic stability when they are used as anode materials.In comparison,the bimetal Sn-based oxides have gained increasing attention in the field of rechargeable sodium ion batteries(SIBs)because of the synergism between the metal components,which prevents agglomeration of the active particles.In this work,the electrochemical performances of copper tin oxide(CuSnO_(3))as an anode material for SIBs were investigated for the first time.
