THE FORCE PARAMETER AND PROFILE CHANGE OF LIQUID BRIDGE BETWEEN TWO UNEQUAL SPHERES—AN EXPERIMENT STUDY

The study of liquid force, which is commonly encountered in nature, has a special meaning to crystallization, removal of heavy metals from wastewater, and particle separation in industry. The Nano UTM T150 tensile machine and CCD camera were used respectively to record the force value and the profile change of liquid bridge between two unequal particles during stretching. The influences of radius ratio and liquid volume on the liquid force-displacement curves, maximum liquid force, and rupture distance were analyzed. And the experiment results were then compared with the calculating results according to the circle hypothesis and Y-L equation. Finally, the deficiency of the circle hypothesis in calculating the liquid force was analyzed, meanwhile, combining the influence of gravity, the changes of liquid profile in the whole process of stretch were further analyzed. The results show that the maximum liquid force was greatly influenced by radius ratio while the rupture distance was influenced by liquid volume a lot. What is more, the circle hypothesis can well predict the maximum liquid force, while its prediction of liquid force during the whole stretch is not accurate, this can be attributed to the fact that the liquid profile cannot be expressed as a ring after the liquid force reaches its maximum. Last but not least, based on the influence of gravity, the changes of liquid profile during the experiment were simplified as a circular to a quadratic parabola when the influence of gravity can be neglected; An ellipse which ratio of the long axis to the minor axis gradually increased when the influence of gravity is in the transition stage or has little impact. And a “cooling tower shape” to a hyperbolic, which upper out curvature is small and lower out curvature is large, when the influence of gravity can not be neglected.