Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature f...Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler.展开更多
In this paper,the field synergy principle is firstly performed on the viscoelastic fluid-based nanofluid and other relevant fluid in channel at turbulent flow state to scrutinize their heat transfer performance based ...In this paper,the field synergy principle is firstly performed on the viscoelastic fluid-based nanofluid and other relevant fluid in channel at turbulent flow state to scrutinize their heat transfer performance based on our direct numerical simulation database.The cosine values of intersection angle between velocity vector and temperature gradient vector are calculated for different simulated cases with varying nanoparticle volume fraction,nanoparticle diameter,Reynolds number and Weissenberg number.It is found that the filed synergy effect is enhanced when the nanoparticle volume fraction is increased,nanoparticle diameter is decreased and Weissenberg number is decreased,i.e.the heat transfer is also enhanced.However,the filed synergy effect is weakened with the increase of Reynolds number which may be the possible reason for the power function relationship in empirical correlation of heat transfer between heat transfer performance and Reynolds number with the constant power exponent lower than 1.Finally,it is also observed that the field synergy principle can be used to analyze the heat transfer process of viscoelastic fluid-based nanofluid at the turbulent flow state even if some negative cosine values of intersection angle exist in the flow field.展开更多
The Cu Cr/1Cr18Ni9 Ti bi-metal materials were prepared by the solid-liquid bonding method. The microstructures, mechanical properties and formation mechanism of the bonding interface were studied. The results show tha...The Cu Cr/1Cr18Ni9 Ti bi-metal materials were prepared by the solid-liquid bonding method. The microstructures, mechanical properties and formation mechanism of the bonding interface were studied. The results show that there exists a serrated transition layer with a certain width at the interface of Cu Cr/1Cr18Ni9 Ti bi-metal materials, and the transition layer consists of Fe-based and Cu-based solid solutions. The elastic modulus and hardness reach the maximum values at the interface closing to the 1Cr18Ni9 Ti zone. The bonding temperature has a significant effect on the width and morphology of the transition layer. The interfacial bonding strength is at least 30% higher than that of the Cu Cr alloy, and the tensile fracture occurs at the side of the Cu Cr alloy rather than at the bonding interface.展开更多
基金Project (50235040) supported by the National Natural Science Foundation of China project( NCET-040753) supportedby the New Century Excellent Talent in University project(20050533037) supported by the Doctoral Programof Higher Education
文摘Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler.
基金supported by China Postdoctoral Science Foundation(Grant No.2014M561037)President Fund of University of Chinese Academy of Sciences(Grant No.Y3510213N00)+2 种基金National Natural Science Foundation of China(Grant No.51276046)Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20112302110020)National Natural Science Foundation of China(Grant No.51325603)
文摘In this paper,the field synergy principle is firstly performed on the viscoelastic fluid-based nanofluid and other relevant fluid in channel at turbulent flow state to scrutinize their heat transfer performance based on our direct numerical simulation database.The cosine values of intersection angle between velocity vector and temperature gradient vector are calculated for different simulated cases with varying nanoparticle volume fraction,nanoparticle diameter,Reynolds number and Weissenberg number.It is found that the filed synergy effect is enhanced when the nanoparticle volume fraction is increased,nanoparticle diameter is decreased and Weissenberg number is decreased,i.e.the heat transfer is also enhanced.However,the filed synergy effect is weakened with the increase of Reynolds number which may be the possible reason for the power function relationship in empirical correlation of heat transfer between heat transfer performance and Reynolds number with the constant power exponent lower than 1.Finally,it is also observed that the field synergy principle can be used to analyze the heat transfer process of viscoelastic fluid-based nanofluid at the turbulent flow state even if some negative cosine values of intersection angle exist in the flow field.
基金supported by the National Natural Science Foundation of China(Grant No.51371139)Science and Technique Innovation Program of Shaanxi Province(Grant No.2012KTCQ01-14)+1 种基金Pivot Innovation Team of Shaanxi Electric Materials and the Infiltration Technique(Grant No.2012KCT-25)Shaanxi Provincial Project of Special Foundation of Key Disciplines
文摘The Cu Cr/1Cr18Ni9 Ti bi-metal materials were prepared by the solid-liquid bonding method. The microstructures, mechanical properties and formation mechanism of the bonding interface were studied. The results show that there exists a serrated transition layer with a certain width at the interface of Cu Cr/1Cr18Ni9 Ti bi-metal materials, and the transition layer consists of Fe-based and Cu-based solid solutions. The elastic modulus and hardness reach the maximum values at the interface closing to the 1Cr18Ni9 Ti zone. The bonding temperature has a significant effect on the width and morphology of the transition layer. The interfacial bonding strength is at least 30% higher than that of the Cu Cr alloy, and the tensile fracture occurs at the side of the Cu Cr alloy rather than at the bonding interface.
