Numerical Simulation On Atomization Process Of Swirl Nozzle Jet

Atomization process of swirl nozzle Jet which has the characteristics of large distribution space and small atomization particle size.The droplet size and spatial distribution provide initial conditions for evaporative combustion,and it affects the combustion characteristics and combustion stability of the engine by affecting the spray combustion process.Therefore,research on the rotating circular liquid jet produced by the swirl nozzle is very important.Previously,most scholars used the interface tracking method to study the primary breakup of the rotating conical liquid film,and the research on the secondary breakup was less.The secondary breakup study of the liquid film is mainly combined with the VOF method and the direct numerical simulation method with a very small cell scale.In this paper,considering the existence of multi-scale and multi-phase flow coupling in the atomization process,the atomization and fracture process of the swirl nozzle was studied by using the cross-scale VTD method.The atomization and fracture of the liquid film can be divided into three zones: a continuous liquid film zone,a primary breakup zone and a secondary breakup zone.The size of the droplets formed by primary breakup is usually on the order of millimeters or more,but the droplet size formed by secondary breakup is usually on the order of micrometers.In this paper,the numerical simulation of the atomization and breakup process of a rotating circular jet is carried out using FLUENT software.The feasibility of VTD method is verified by numerical simulation of transverse jet.The simulation results of VTD method under different turbulence models and VTD、VOF、DPM method are compared.In this paper,the rotating circular liquid jet as the research object,analyzes the evolution process of the rotating conical liquid film formed by the jet and fully develops the fracture morphology of the liquid membrane,and studies the gas-liquid interaction of the liquid membrane.The different modes of action between the non-rotating and rotating conical liquid film and the ambient gas are discussed.It is considered that the circumferential surface wave structure caused by centrifugal force is the main reason for the difference of atomization morphology.The end of this paper,the influence of different viscous liquid,axial velocity and jet velocity on the angle of atomization cone and the area of breakup is analyzed.The results show that the atomization of liquid with low viscosity and density is more violent,and the continuous region is shorter.The crushing length increases with the increase of axial velocity and shortens with the increase of circumferential velocity.