Direct Numerical Simulation Of Droplet Breakup Characteristics During Vaporization Based On CLSVOF

In order to investigate the influence of environment and fuel properties on droplet evaporation characteristics,from the perpective of droplet breakup,a model for the direct numerical simulation of evaporating,deforming droplets is presented.The coupled level set and volumn-of-fluid method is applied to arbitrarily shaped interfaces,which may collide and break up.Jump conditions like phase change and fuel property difference at the interface are smoothed to take account of their effect on heat and mass transfers and momentum diffusion.Validation comprises a 1D test case and the vaporization of an isolated static drop for interfacial heat and mass transfer,and droplet oscillations for the surface tension.Firstly,the effect of convective environment on droplet evaporation characteristics has been investigated.In the weak convective environment(V_rel=1m/s),the boundry layers around the droplet deform.The layer thickness in front of the droplet remains,while that behind increases.In the strong convective environment(V_rel=20 m/s,We=96.98,Oh=0.0116),the droplet deforms in the mode of sheet-thinning.Compared with classical droplet evaporatin model,the present code can simulate the changing boundary layer and droplet shape.And then taken emulsion fuel?water-hexadecane?as the research object,the effect of fuel boiling point on droplet evaporation characterisitics has been investigated through putting one or several bubbles of a certain size in droplet.Varying the initial droplet size,and the initial size and number of explosive boiling bubble,the droplet breakup processes has been well revealed.At last,the synergistic effects of convective environment and fuel boiling point on droplet deformation and breakup have been investigated.By changing the relative position of initial bubble and the environmental flow,the influence of convection environment on bubble growth has been explored,and the possibility of bubble breakup and sheet-thinning during droplet evaporation has been analyzed.