Retracted article – Experimental study on dynamic deformation of free surface under surrounding gas flow
MATEC Web of Conferences
Experimental study on dynamic deformation of free surface under surrounding gas flow
Ruquan Liang 0
Xiaoyuan Li 0
linyang Zhu 0
Zhihui Zhang 0
0 Key Laboratory of National Education Ministry for Electromagnetic Processes of Materials, Northeastern University in ShenYang , CN
In this paper, the dynamic deformation of the free surface of the liquid bridge caused by the surface shear flow is studied experimentally 5cSt (Prandtl number Pr=68) is taken as the material of liquid bridge and nitrogen as the airflow. The shape of the liquid bridge is captured by a high-speed camera and processed by MATLAB. The boundary extraction technique is used to obtain the coordinate points of the liquid bridge surface. The volume ratio of the liquid bridge and the shear flow velocity have a vital influence on the deformation of the free surface. When the direction of the airflow is against as the gravity and the volume ratio is 1, the deformation magnitude of the free surface decreases with the increase of volume ratios. In this process, the deformation curves always present a sinusoidal pattern.
1 Introduction
The dynamic deformation of the free surface of liquid
bridge is closely related with production of high-quality
single crystal in floating zone method. Therefore, the
conclusion driven by this paper can directly apply to the
growth of melt crystal. In physical experiments, we use
the ideal isothermal model to improve the quality of
silicon crystal. Deformation of an isothermal interface is
extremely related to a co-axial gas flow when enter from
the bottom to the top, which was discussed by
Gaponenko[1,2], and they reported that the linear velocity
of gas almost determined the free surface deformation.
The tendency that surface deformation grows with the
volume ratio V quasi-linearly was predicted by
Gaponenko[3]. After a slow decaying of the period, the
new oscillations are generated. The new liquid bridge
decayed much faster. A linear dependence is not
observed for all volume ratios, despite the small Reynolds
number (280 < Reg < 560) is studied by Matsunaga[4]. The
dynamic deformation displays a strong dependence on
the liquid volume ratio and the direction of the gas stream
parallel to the interface. The shape of liquid bridge which
exists between two fixed support columns is usually
maintained to be cylindrical by surface tension. In this
paper, the experiment is carried out about dynamic
deformation of free surface under the normal gravity
environment. The object of this experiment is to study the
adiabatic gas-liquid two-phase flow system with
isothermal and cylindrical geometry. The dynamic
deformation of the free surface of the liquid bridge is
studied.
2 Experiment Establishment and
Experiment Process
The equipment includes a high-speed camera, a liquid
bridge support frame, a astigmatism film and a back light.
The liquid bridge generation equipment is fixed on the
horizontal experimental platform to adjust the liquid
bridge to proper height. The micro-syringe is used to
control the primary volume of silicone oil. The cylinder
the sleeve, the white back light, the camera and the liquid
bridge generation equipment are all set to be ready. Then,
the gas enters the cylinder sleeve, after the ventilation is
stable; the high-speed camera begins to shoot the shape
of liquid bridge. The coordinate point data of liquid
bridge surface is obtained by using boundary extraction
technology and numerically simulated by ORIGIN
software to form the figures, and the dynamic
deformation of free surface of liquid bridge is acquired.
In the experiment, the aspect ratio of liquid bridge is
defined as Γ =d/R0, where d and R0 denote the height and
support radius, respectively. Figure 1 is a simple diagram
of the experiment.
The liquid bridge is surrounded by a vertical
transparent glass sleeve with R0=3mm and Rout=5mm
remaining unchanged. Gas enters the glass sleeve from
the lower part and flows through the annular tube of size.
Rh= 2
Rout - R0
Reg=2
Rout R0 U0/Vg
(1)
(2)
With constant flux Q. Reynolds number Reg is
determined by hydraulic diameter, Digital images are
acquired at 50 frames/seconds for 5 seconds. The stable
shape of liquid bridge can be obtained by calculating the
mean value of these images. Repeat above process for
each gas flux.
The free surface contour is determined by the physical
parameters of bilateral liquid and geometric parameters of
the system. But generally, the effect of flow on the
dynamic deformation of free surface is usually described
by the capillary number Ca[5].
Ca = 6.0
10 4U0G2 f (V )
Ca = vg
gU0
f (R0, Rout , d ,V )
The coefficient is determined by the volume ratio V
and the gas velocity U0. When the aspect ratio is Γ =1,
the coefficient decreases from 1 to 0.5 with the volume
ratio increasing from 0.8 to 1.07. The capillary number
increases with the airflow velocity increasing from 1m/s
to 2m/s. The predicted dynamic deformation of the free
surface is (...truncated)