The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic t...The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic tension-compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 （molar fraction, %）, which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1 Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.展开更多
Based on isentropic flow and thermal equilibrium assumptions, a model was derived to calculate discharge flow rate, which unified the rules of room temperature water discharge, high temperature and high pressure water...Based on isentropic flow and thermal equilibrium assumptions, a model was derived to calculate discharge flow rate, which unified the rules of room temperature water discharge, high temperature and high pressure water discharge, two-phase critical flow, saturated steam and superheated steam critical flow, and gave a method to calculate critical condition. Because of the influence of friction, the entropy is increased in the actual discharge process, and the discharge flow rate in thermal equilibrium condition can be obtained by the original model multiplied by an appropriate correction coefficient. The model calculated results agreed well with the experiment data of long nozzle critical flow.展开更多
Numerical simulations have been carried out to investigate the liquid atomization and spray process using the Discrete Phase Model of the commercial CFD code combined with the Wall-Film boundary conditions. The effect...Numerical simulations have been carried out to investigate the liquid atomization and spray process using the Discrete Phase Model of the commercial CFD code combined with the Wall-Film boundary conditions. The effects of spray parameters on droplets Santer mean diameter （SMD）, droplet collision speed, the thickness of liquid-film, the surface temperature and its uniformity were analyzed in the present study. The simulation results and the experimental data obtained in the available literature agree within 13.8%, The computational results show that the spray pressure is the main factor to realize the atomization. Increasing the mass flux and the spray pressure, the droplet collision speed increases while the corresponding maximum film thickness on the heated surface declines. The surface temperature changes indistinctively with the increase of the spray distance, but the temperature distribution tends to be uniform.展开更多
This article presents the results of experimental investigation of heat transfer process, carded out using the model of heat exchanger. Two-phase statically stable foam flow was used as a heat transfer fluid. Heat exc...This article presents the results of experimental investigation of heat transfer process, carded out using the model of heat exchanger. Two-phase statically stable foam flow was used as a heat transfer fluid. Heat exchanger model consisted of staggered tube bank. Experimental results are presented with the focus on influence of tube position in the line of the bank, volumetric void component and velocity of gas component of the foam. The phenomena of liquid draining in cellular foam flow and its influence on heat transfer rate has also been discussed. The experi- mental results have been generalized by relationship between Nusselt, Reynolds and Prandtl numbers.展开更多
基金supported by the project"Development of Key Technology for Next-generation Heat-resistant Magnesium Alloys,Kumamoto Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence"from Japan Science and Technology Agencyby funds from the"Priority Assistance of the Formation of Worldwide Renowned Centers of Research-The 21st Century COE Program and Global COE Program(Project:Center of Excellence for Advanced Structural and Functional Materials Design)"a Grant-in-Aid for Scientific Research and Development from the Ministry of Education,Culture,Sports,Science and Technology of Japan
文摘The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic tension-compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 （molar fraction, %）, which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1 Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.
文摘Based on isentropic flow and thermal equilibrium assumptions, a model was derived to calculate discharge flow rate, which unified the rules of room temperature water discharge, high temperature and high pressure water discharge, two-phase critical flow, saturated steam and superheated steam critical flow, and gave a method to calculate critical condition. Because of the influence of friction, the entropy is increased in the actual discharge process, and the discharge flow rate in thermal equilibrium condition can be obtained by the original model multiplied by an appropriate correction coefficient. The model calculated results agreed well with the experiment data of long nozzle critical flow.
基金supported by National Natural Science Foundation of China (No.50776087).
文摘Numerical simulations have been carried out to investigate the liquid atomization and spray process using the Discrete Phase Model of the commercial CFD code combined with the Wall-Film boundary conditions. The effects of spray parameters on droplets Santer mean diameter （SMD）, droplet collision speed, the thickness of liquid-film, the surface temperature and its uniformity were analyzed in the present study. The simulation results and the experimental data obtained in the available literature agree within 13.8%, The computational results show that the spray pressure is the main factor to realize the atomization. Increasing the mass flux and the spray pressure, the droplet collision speed increases while the corresponding maximum film thickness on the heated surface declines. The surface temperature changes indistinctively with the increase of the spray distance, but the temperature distribution tends to be uniform.
文摘This article presents the results of experimental investigation of heat transfer process, carded out using the model of heat exchanger. Two-phase statically stable foam flow was used as a heat transfer fluid. Heat exchanger model consisted of staggered tube bank. Experimental results are presented with the focus on influence of tube position in the line of the bank, volumetric void component and velocity of gas component of the foam. The phenomena of liquid draining in cellular foam flow and its influence on heat transfer rate has also been discussed. The experi- mental results have been generalized by relationship between Nusselt, Reynolds and Prandtl numbers.
