Study On Dynamic Deformation Of Free Surface For Liquid Bridge Caused By Surrounding Gas Flow

The floating zone method is provided for growing the high quality crystal,this method is also considered as the most effective and advantageous method for the preparation of space materials.It is helpful for improving the floating zone method through studies on flow field of the liquid bridge caused by surrounding gas flow,so the influence of the surface shear flow on the stability of the liquid bridge is becoming the focus of modern space science.In this paper,free surface deformation of the liquid bridge caused by the surface shear flow is studied by experiment.In the international,the research on the dynamic deformation of the free surface for liquid bridge is gradually concerned,and the research on the dynamic deformation of the free surface for the liquid bridge caused by the surface shear flow is just starting.In this study,the research on the dynamic deformation of the free surface for liquid bridge is carried out in the domestic first.The blank of the research is filled The medium of the liquid bridge in the experiment is 5cSt silicone oil(Planck number Pr=68),and the medium of surrounding gas flow is nitrogen.The experiment was carried out under normal gravity.The control variables include the velocity of the shear flow,the direction of the shear flow and the volume of the liquid bridge.Because the experiment is carried out under normal gravity,the static deformation of liquid bridge is inevitable.The images of the liquid bridge obtained in the experiment are preprocessed so as to get ideal image effect.The free surface coordinates are extracted through the MATLAB program,so the free surface deformation of the liquid bridge is obtained.These optical images are obtained by high-speed camera,and the analysis on them can make the research size reach micron level.In this paper,a series of experiments are carried out by controlling the volume of the liquid bridge and the size and direction of the shear flow,the following results are obtained:1.The shear force generated by the surface shear flow is important in the experiment,and for some volume of liquid bridge the free surface deformation is linear with the velocity of the shear flow.The free surface dynamic deformation of the liquid bridge is linear increase when other variables are certain and the shear flow velocity increases from 1m/s to 2m/s gradually.2.The volume of the liquid bridge and the parallel shear flow have important influence on the surface deformation of the liquid bridge.When the direction of the gas flow is in the same direction as the gravity,and the aspect ratio is 1,the deformation of the free surface decreases with the increase of volume,before the critical volume ratio 0.862.The deformation increases with the increase of the volume ratio,when exceeding this volume ratio.In this process the shape of the deformation curve is always similar to the sine curve.When the direction of gas flow is opposite to gravity,and the aspect ratio is 1,the deformation of the free surface decreases with the increase of volume,before the critical volume ratio 0.979.The deformation increases with the increase of the volume ratio,when exceeding this volume ratio,and the deformation curve is similar to the shape of bimodal curve.The dynamic deformation of the free surface is similar to the former when the aspect ratio is 1.2,and the critical volume ratio is 0.939.3.The volume of the liquid bridge volume and gravity level determine the shape of liquid bridge,the difference of this shape affects the distribution of the shear flow,and then can change the internal flow of the liquid bridge.