Numerical Simulation Of The Break-up And Atomization Process Of The Impinging Liquid Jets

In this paper,Adaptive Mesh Refinement(AMR)adaptive mesh technology and Volume of Fluid(VOF)model are used to simulate the atomization process of the two impinging jets,which aims to analyze atomization characteristics of the impinging fuel injector applied in the liquid rocket engine.The effects of different jet velocity,impact angle,jet velocity ratio and jet diameter ratio on the characteristics of impinging jet atomization are obtained.The two jet flows from injection,collision and crushing,and the jets are formed into liquid droplets and finally break into droplets.Results show that,Weber(We)number of the jet determines the atomization mode,and the liquid film is stable when We is small,and the instability is not obvious,the liquid film remains closed.The surface instability of the liquid film increases with the increase of We,the impact wave becomes obvious on the surface of the liquid film,and then develops gradually to the downstream,and finally induces the flake of the liquid ligaments from the liquid sheet.The liquid ligaments will then break into droplets with the contribution of aerodynamic force,which finally leads to liquid jet atomization.As for the specific working parameters,the increase of the impact angle will lead to the decrease of liquid sheet break-up distance,the increase of atomization area angle and impact wave wavelength.However,the liquid sheet length,width,length-width ratio,and impact wave frequency decreases with the increase of impact angle.When jet speeds are inconsistent,the liquid sheet forms as a whole "bow",the jet with higher speed determines the development of the entire atomization field.When the diameter of the two jets is not coincide,the liquid sheet will sink to the jet with a smaller diameter,showing a tendency to "wrap" the smaller jet,and the impact wave on the liquid sheet surface becomes insignificant.In addition,this paper also explores the effects of some parameters on the process of impinging jet atomization,parameters of which can not be studied in experiments,such as,jet boundary layer and liquid viscosity(univariate).The results show that the existence of the jet boundary layer will induce some obvious unstable fluctuation on the jet surface before the jets impinge together.The existence of jet boundary layer will also make the amplitude of the unstable fluctuation of the liquid sheet increase greatly,the wavelength become longer,the wave velocity decrease and the frequency decrease.On the other hand,the viscosity has an impediment to the development of the atomization process,when the viscosity of the liquid can not be ignored,the critical transition Weber number of different atomization models will increase.