Research Of Rising Bubble Behavior In Sloshing Conditions

Waves, earthquakes and other conditions can lead to liquid sloshing in nuclear devices with presence of free surface. In order to analyze the characteristics of bubble rising behavior in sloshing condition and analyze the influence of sloshing to rising bubble, this paper uses CLSVOF (Coupled Level-Set and Volume-Of-Fluid) model based on fluent platform to numerical simulate bubble rising in liquid.The paper researches the bubbles rising process in sloshing condition with numerical simulation, and then we analyze the behavior characteristics of rising bubbles with experimental results. The results show that a violent sloshing will affect the bubble escaping size from inlet, and will accelerate portion of bubbles separate from others, make the two bubbles to one bubble; Sloshing movement will cause a relatively large deviation from the displacement in horizontal direction, then the bubbles rise in a cyclical swing. The results prove that under sloshing conditions the liquid inside a large space exhibit complex nonlinear eddy current field. The field leading spiral rising bubbles into swing rising, the influence of field to rising bubbles is far greater than the bubbles'own physical attributes.Numerical simulation the process of single bubble rising in condition of still water? surging absence of free surface, and sloshing, than analyzes the changing of its speed. The simulated results show that the additional inertial force from surging reduce the bubble rise velocity, the horizontal direction velocity variation trend similar to the additional inertial force, the changing rate decreases with the bubbles'size decreasing, the frequency increases with the bubbles' size decreasing; Free liquid surface fluctuations in the vertical direction causes the resistance on the bubbles'rising velocity, superimposed with an additional inertial force in the horizontal direction makes the bubble velocity changing more complex. The results prove that the impact of sloshing is superimposed by additional inertial forces and free surface fluctuations. The velocity of the bubble depends on the form and intensity of external stimulus?the fluctuations of free surface, the bubbles property itself played a secondary role.Numerical simulation the process of bubbles' rising in sloshing condition with different cycle and amplitudes, analyze the variation of bubble velocity changing with the period and amplitude increases. Simulations show that with the increasing of sloshing amplitude, the magnitude of bubble swing in horizontal increase first and decrease later, in vertical decrease first increase later then decrease again, the velocity trend similar to external force. With the increasing of cycle the magnitude of bubble swing in horizontal decreases rapidly, the velocity in vertical decrease first increase later. The results prove that although the increasing of sloshing amplitude cannot change the overall direction of the movement trends, but enhance the local disturbance, so the changing of bubble swing amplitude shows a significant non-linear relationship. The changing sloshing cycle will change the phase of external force, and change the bubbles movement trend in horizontal and then cause a great extent on bubble swing. The bubble velocity in horizontal is more sensitive to the sloshing cycle.Due to the complex nonlinear movement of free surface fluctuations, the velocity in vertical also reflects the strong nonlinearity with the sloshing amplitude and period changed.