Deformation And Fragmentation Characteristics Of Droplets In Jet Flow

The drop breakup plays a significant role in several aspects including energy transform and environment.In this thesis,simulation analysis was completed to help understand the drop breakup in flow fluid by utilizing the Fluent software and the coupled method of LES and VOF.By comparing the set of experimental data,it is found that this method is suitable for analyzing the drop breakup in flow fluid.This method is designed mainly to analyze the drop breakup,deformation and time characteristics caused by fluid structure,pressure distribution and the drop physical property respectively.Several results are obtained:Firstly,influenced by the pneumatic pressure in fluid flow,the drop would break up when the pneumatic pressure is higher than the surface tension and viscous force of the drop itself,but at the same time vortex occurs at the back of the drop.When the flow continues affecting,the generated pressure will deform the drop.Secondly,the initial diameter of the drop affects the drop breakup a lot,the larger initial diameter of the drop,the more difficult for breakup.Thirdly,the viscocity,type,coefficient of surface tension and gravity will all have effects on drop breakup.However,when the drop has a specific velocity in vertical direction,the drop breakup in fluid flow cannot be defined by single breakup method,it is more similar to multimode breakup.Fourthly,d_cro/d₀ and d_str/d₀ stands for the maximum deformation of drop.In general,d_cro/d₀ would first increase and then decrease with the increasing of We,but d_str/d₀ keeps dropping at the same situation.d_cro/d₀ also decreases with the increasing diameter of the drop,which means when the initial diameter of drop getting larger,the drop already break up before reaching the maximum deformation.Fifthly,the drop breakup time shortens with the increasing We,this also means that it is harder to break up with larger initial diameter.Furthermore,the drop breakup time shortens more slowly when the We increases.This means that the effect on drop breakup time caused by flow velocity is getting weaker when We is quite high.