The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such pa...The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such particles, there are few results for cuboids. This paper presents data for cuboids with a square base in static glycerin-water solutions of various volume concentrations. Complex motions were observed and characterized. A dimensionless expression is given for terminal velocity ut as a function of Archimedes number Ar which is used to develop an accurate correlation for friction factor CD. The accuracy of the correlation is 7.9% compared to experimental data in the literature. For both square plates and square rods, the terminal velocity per unit mass, ut/mp, was used to characterize the influence of narticle geometry on velocity, which was shown to be linear.展开更多
In the conventional melt preparation of magnesium rare-earth(Mg-RE)alloys,the repeated heating/cooling process involved in grain refinement and flux refining usually prolongs the preparation period and aggravates melt...In the conventional melt preparation of magnesium rare-earth(Mg-RE)alloys,the repeated heating/cooling process involved in grain refinement and flux refining usually prolongs the preparation period and aggravates melt oxidation.In this work,the purification and grain refinement of Mg-9Gd-3Y(GW93)alloy was simultaneously realized by one-step refining at 740℃ by using a self-developed compound flux.The results show that,only after holding for 10 min,the inclusion content of the alloy is reduced by 81%to 0.29%,while the grain size is reduced by 84%to 119μm.A physical model depicting the interactions between compound flux and alloy melt was proposed based on thermodynamic calculation and microstructure observation.The grain refinement mechanism has been analyzed by considering the presence of Zr particle(Zr_(p))and Zr solute(Zr_(s)).In addition,the generated RECl_(3) was found to be readily absorbed by the flux,decreasing the surface tension and promoting the purification efficacy of the flux,which plays an important role in the promoted elongation of the as-cast Mg-9Gd-3Y-0.5Zr(GW93K)alloy.This work presents a unique prospect in simplifying the melt preparation of Mg-RE alloy with a promoted quality.展开更多
基金supported by the Major Program of the National Natural Science Foundation of China with Grant No. 10632070
文摘The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such particles, there are few results for cuboids. This paper presents data for cuboids with a square base in static glycerin-water solutions of various volume concentrations. Complex motions were observed and characterized. A dimensionless expression is given for terminal velocity ut as a function of Archimedes number Ar which is used to develop an accurate correlation for friction factor CD. The accuracy of the correlation is 7.9% compared to experimental data in the literature. For both square plates and square rods, the terminal velocity per unit mass, ut/mp, was used to characterize the influence of narticle geometry on velocity, which was shown to be linear.
基金supported by the National Natural Science Foundation of China(Nos.U2037601 and 51821001)the Research Program of Joint Research Center of Advanced Spaceflight Technologies(No.USCAST2020-31).
文摘In the conventional melt preparation of magnesium rare-earth(Mg-RE)alloys,the repeated heating/cooling process involved in grain refinement and flux refining usually prolongs the preparation period and aggravates melt oxidation.In this work,the purification and grain refinement of Mg-9Gd-3Y(GW93)alloy was simultaneously realized by one-step refining at 740℃ by using a self-developed compound flux.The results show that,only after holding for 10 min,the inclusion content of the alloy is reduced by 81%to 0.29%,while the grain size is reduced by 84%to 119μm.A physical model depicting the interactions between compound flux and alloy melt was proposed based on thermodynamic calculation and microstructure observation.The grain refinement mechanism has been analyzed by considering the presence of Zr particle(Zr_(p))and Zr solute(Zr_(s)).In addition,the generated RECl_(3) was found to be readily absorbed by the flux,decreasing the surface tension and promoting the purification efficacy of the flux,which plays an important role in the promoted elongation of the as-cast Mg-9Gd-3Y-0.5Zr(GW93K)alloy.This work presents a unique prospect in simplifying the melt preparation of Mg-RE alloy with a promoted quality.
