The Schlieren technique coupling with a differential interference microscope was applied to visualize the KNbO_(3) melt motion in a loop-shaped Pt wire heater.The natural convection in KNbO_(3) melt was traced by obse...The Schlieren technique coupling with a differential interference microscope was applied to visualize the KNbO_(3) melt motion in a loop-shaped Pt wire heater.The natural convection in KNbO_(3) melt was traced by observing the movement of the tiny KNbO_(3) crystals(~10μm)and the stream velocities of these tracer crystals were measured.In theoretical analysis,the Navier--Stokes equation was solved as a stable field.The general solution for this system of the differential equation was expressed by an approximate power series of azimuth and radius vector.The expression was substituted in the differential equation;a non-trivial solution was obtained exactly.The velocity distribution in the vertical section was obtained which is in qualitative agreement with the experimental result.展开更多
We have investigated experimentally and theoretically the thermocapillary convective flow phenomena in a loop-shaped Pt wire heater of KNbO_(3)(20wt.%)and Li_(2)B_(4)O_(7) solution.Optical evaluations in connection wi...We have investigated experimentally and theoretically the thermocapillary convective flow phenomena in a loop-shaped Pt wire heater of KNbO_(3)(20wt.%)and Li_(2)B_(4)O_(7) solution.Optical evaluations in connection with thermocouple measurements made it possible to get a new type of thermocapillary convective flow in the considered system.To study the kinematical behavior of thermocapillary convection,we have measured the stream velocities of flow.In a theoretical analysis,the flow velocity due to thermocapillary effect alone was estimated by balancing the surface tension forces by viscous forces.The velocity distribution in the solution near the margin of the heater was obtained,which is in agreement with the experimental result.展开更多
To check consciously the crystallization processes,one must control precisely the experimental conditions,one of which is the perfection of the seed crystals.The experimental procedures for growing nearly perfect salo...To check consciously the crystallization processes,one must control precisely the experimental conditions,one of which is the perfection of the seed crystals.The experimental procedures for growing nearly perfect salol seed crystals are described.A seed crystal of rhombic form with less than 10μm in thickness has a threshold supercooling for crystal growth and is very suitable for in situ observations on growth from melt.展开更多
By measuring the temperature of the crystallization front of salol by means of in situ observations on a thermally regulating stage, we have obtained the linear form of (TS/L-TM.B),i.e., the difference between the tem...By measuring the temperature of the crystallization front of salol by means of in situ observations on a thermally regulating stage, we have obtained the linear form of (TS/L-TM.B),i.e., the difference between the temperatures of the front and the melt block vs v, the solidified volume of the interface per second.展开更多
基金Supported by a grant for key research project of microgravity science from the State Science and Technology Commission of China(95-Yu-34)the National Natural Science Foundation of China under Grant No.59832080National Space Development Agency of Japan(NASDA).
文摘The Schlieren technique coupling with a differential interference microscope was applied to visualize the KNbO_(3) melt motion in a loop-shaped Pt wire heater.The natural convection in KNbO_(3) melt was traced by observing the movement of the tiny KNbO_(3) crystals(~10μm)and the stream velocities of these tracer crystals were measured.In theoretical analysis,the Navier--Stokes equation was solved as a stable field.The general solution for this system of the differential equation was expressed by an approximate power series of azimuth and radius vector.The expression was substituted in the differential equation;a non-trivial solution was obtained exactly.The velocity distribution in the vertical section was obtained which is in qualitative agreement with the experimental result.
基金Supported by the Foundation for Kay Research Project of Microgravity Science of the State Science and Technology Commission of China(95-Yu-34)the National Natural Science Foundation of China under Grant No.59832080National Space Development Agency of Japan(NASDA).
文摘We have investigated experimentally and theoretically the thermocapillary convective flow phenomena in a loop-shaped Pt wire heater of KNbO_(3)(20wt.%)and Li_(2)B_(4)O_(7) solution.Optical evaluations in connection with thermocouple measurements made it possible to get a new type of thermocapillary convective flow in the considered system.To study the kinematical behavior of thermocapillary convection,we have measured the stream velocities of flow.In a theoretical analysis,the flow velocity due to thermocapillary effect alone was estimated by balancing the surface tension forces by viscous forces.The velocity distribution in the solution near the margin of the heater was obtained,which is in agreement with the experimental result.
文摘To check consciously the crystallization processes,one must control precisely the experimental conditions,one of which is the perfection of the seed crystals.The experimental procedures for growing nearly perfect salol seed crystals are described.A seed crystal of rhombic form with less than 10μm in thickness has a threshold supercooling for crystal growth and is very suitable for in situ observations on growth from melt.
文摘By measuring the temperature of the crystallization front of salol by means of in situ observations on a thermally regulating stage, we have obtained the linear form of (TS/L-TM.B),i.e., the difference between the temperatures of the front and the melt block vs v, the solidified volume of the interface per second.
