Study On The Calculation Method Of Two-phase Flow Under Electric Field

The gas-liquid multi-media fluid flow with bubbles as the dispersed phase is widely existed in practical engineering fields such as energy,petroleum,power,and chemical industry.The application of an external electric field prov ides an effective way to actively control the dynamic behavior of bubbles without contact.However,there are many problems in the simulation study of the motion behavior of bubbles under an electric field,such as large calculation amount,low computation al efficiency and low accuracy.Therefore,it is very important to study high-efficiency calculation method to solve the two-phase flow model under an electric field.In this study,based on different calculation methods,gas-liquid two-phase flow is taken as the research object.By coupling the continuity equation of incompressible fluid,Navier-Stokes equation,electric field equation and other control equations,a multi-field coupling model for rising bubbles in viscous fluids is established,and numerical simulation is carried out.The two-phase popularity of coupled electric field is studied,and the effect of electric field on bubble motion is analyzed.The main research contents and conclusions are as follows:1.The Level-set(Level-set)and phase field method(Phase-field)are used to track the changes of deformation and rupture during the rising of the bubble.The accuracy and validity of the two methods are verified by mass conservation.At the same time,the calculation area is determined for the accuracy of calculation,and the optimal mesh size is calculated by using mesh independence test.2.Compared with the Level set method,the phase field method has a certain improvement in the calculation efficiency and accuracy.Among them,the calculation efficiency of the phase field calculation method in the same grid is increased by 5 times,and 3 times in the vertical electric field environment.Moreover,the phase field method is easier to capture the slight changes of bubbles in the process of during the rising of the bubble,and the quality of the simulation results is better,which verifies the validity of the phase field calculation method.3.The simulation analysis of bubble rising process under coupled electric field by two methods shows that under the interaction of electrostatic force,buoyancy and surface tension,the bubble is stretched into an ellipsoid along the direction of the electric field line,and the ratio of the length to the short axis is proportional to the applied electric field strength.In addition,the bubble rising velocity is affected by the electric field,and the vertical electric field accelerates the rising of the bubble and decelerates in the horizontal direction.4.Phase field method is used to study the motion and coalescence of a pair of coaxial bubbles under an external uniform vertical electric field,and the effects of different electric field strengths on the interaction and coalescence of rising bubbles.The results show that the uniform electric field accelerates the collision and coalescence process of double bubbles in the fluid,and increases the rising velocity of the coalesced bubble.When the electric field strength is strong,the coalesced bubble will rupture,and the time rupturing also decreases with the increase of electric field strength.The phase field method is compared with the simulation results of LBM(Lattice Boltzmann method),and the shape of the bubble obtained by two methods is in good agreement,which verifies the correctness of the calculation model.