Numerical Simulation And Experimental Rearch Of Single Bubble Breakup In Turbulent Flow

Bubble breakup is a common phenomenon in multiphase flow reator,bubble can significantly increase the gas-liquid contact area which can promote the transfer of mass,heat and momentum.The bubble breakup phenomenon plays an important role in the multiphase flow reactor.In this study,CFD software is used to simulate the jet flow field in the plexiglass rectangular tank and the behaviour of single bubble in the turbulent flow field.Furthermore the related analysis content is carried on in this paper.High speed camera technology and 2D PIV(Particle Image Velocimetry)are respectively used in the experimental research to obtain the relevant information of flow field and bubble.At the same time,the simulation for 2D and 3D structure,different mesh sizes and turbulence models are carried out by using ANSYS software.In this study the optimal simulation method is selected through the comparison of simulation results and experimental results of liquid flow field and bubble breakup.Results show that the way of using structural grids and the LES-VOF method can relatively be in conformity with the experimental result and simutaneously obtained the accurate process of bubble breakup.In the numerical simulation,the parameters such as the jet flow velocity,bubble size and initial generating position of bubble are changed to analyze the breakup situations.The simulation results of deformation and probability of bubble are compared with experimental results.At the same,the trajectories of bubbles,the number of sub-bubbles,surface area,the largest stable bubble size and the gas-liquid interaction and so on are carried on the corresponding analysis.Based on the interaction between liquid flow and bubble,the force of bubble at bubble breakup moment are analyzed.Found that the shear stress of bubble neck is significantly larger than other parts of bubble at the moment.Through the analysis of the surround flow field found that when the surface turbulent pressure is greater than the surface force,the bubble will breakup.A critical weber number formula is put forward according to the features of liquid flow field around bubble.When the number is greater than 0.5,the bubble will breakup.