Numerical Study On The Droplet Impact Process

Droplet impact process is a typical free surface problem and widely exists in many engineering fields.In general,the impact targets of droplet are divided into dry wall,thin liquid film and deep pool.When droplet impacts on the dry wall or deep pool,it involves the interaction of droplet-wall or droplet-film,while when droplet impacts on thin liquid film,it involves the interaction of droplet-film-wall,which results in different mechanisms of droplet impacting on different target surfaces.For droplet impact problem,a three-dimensional incompressible laminar flow calculation model is established.Based on the coupled level set-fluid volume method,the two-phase interface is tracked.The accuracy of the numerical method is verified by comparing with the experimental pictures and data in the literature.On this basis,the impact process of droplet impacting different target surfaces is studied.Droplet impacts on dry wall: with the increase of droplet viscosity,surface tension coefficient,and incidence angle,the spreading factor decreases;with the increase of droplet density,diameter and velocity,the spreading factor increases.Droplet impacts on static liquid film: with the increase of liquid film thickness,crown height and inner diameter first increase and then decrease;with the increase of droplet velocity,crown height and inner diameter increase.Droplet impacts on moving liquid film: with the increase of liquid film velocity,crown upstream height and inner diameter increase,downstream height decreases;with the increase of liquid film thickness,crown upstream and downstream height and inner diameter first increase and then decrease;with the increase of droplet diameter and speed,crown upstream and downstream height and inner diameter increase.Droplet impacts on dry rotating sphere: with the increase of viscosity and incidence angle,the spreading factor decreases;with the increase of droplet velocity and diameter,the spreading factor first increases and then decreases;the rotational speed of the sphere has little effect on the spreading factor.Droplet impacts on wetting rotating sphere: with the increase of liquid film thickness,crown height and inner diameter first increase and then decrease;with the increase of droplet velocity,crown height first increases and then decreases,crown inner diameter decreases;with the increase of droplet diameter,crown height and inner diameter increase;with the increase of rotational speed,crown height first increases and then decreases,crown inner diameter slightly increases;with the increase of incident angle,crown height and inner diameter decrease.