Studies On Off-center Collisions Of Binary GaInSn Metal Droplets In Uniform Flow

Droplet collision behavior is widespread in natural phenomena,industrial production,and biomedical science.In this paper,the numerical simulation and experimental study of liquid metal droplet off-center collision are carried out.Based on the Open FOAM computing platform,numerical simulation of the collision behavior of metal droplets in the gas is analyzed.Deposition and collision processes are studied experimentally by gallium alloy(Ga In Sn)liquid metal.The specific research work can be divided into the following two parts:Firstly,based on collision mechanism of droplets,a high-speed imaging experimental platform for liquid metal droplets sedimentation in the liquid phase was established to study the effects of droplet diameter and surface tension on the collision results.The experimental results were analyzed by the contact angle,contact time,and spread factor.The experimental results showed that with the increase of impact velocity,metal droplets appear successively after the collision: coalescence,coalescence accompanied by rebound,and rebound.There is a critical impact velocity between the rebound and coalescence,which is related to the surface tension and particle size of the metal droplets.Under rebound mode and coalescence mode,the fitting formulas of dimensionless contact time(τc)and contact time(tc)are obtained,respectively.We analyze the mechanism of coalescence,and find that mechanical oscillations occur in the process of coalescence,which will lead to the variation of the inherent surface tension.The higher the impact velocity,the greater the variation of surface tension.The relationship of maximum spreading factor(βm a x)and Weber number is obtained during coalescence.Secondly,the collision process of the metal droplet in the gas phase is simulated numerically by using Coupled Level-Set and Volume-Of-Fluid method(CLSVOF)and adaptive mesh refinement(AMR)technology.The results showed that the mod el of metal droplets after the collision is different from water droplets under high Weber number.Liquid metal droplets have unique collision results: break up after finger,stretching separation with finger pinching,and break up after stretching separation.With the increase of Collision parameter,the mode of the metal droplet will transition from break up after finger to stretching separation with finger pinching,and finally evolve to break up after stretching separation.The larger the contact area during impacting is,that is,the larger the collision parameters are,the larger the surface energy obtained from kinetic energy after the droplet collision is.When the droplets are in the stretching separation with finger pinching mode,the larger the collision parameter,the smaller the kinetic energy in the late collision stage.With the increase of Weber number,the metal droplets transition from stretching separation to break up after stretching separation after collision.The experimental and simulation results are analyzed by relevant dimensionless parameters to study the internal mechanism of metal droplet collision,which provides a research basis for the innovation of practical engineering technology.