Evolution Process of Thermal Properties of Liquid Film Impinged by Double Droplet Based on Lattice Boltzmann Method
In order to investigate the characteristics of wall heat flow density distribution in the process of side-by-side double droplets impinging on the high temperature wall covered with liquid film,the effects of droplet spacing,impact velocity and liquid phase viscosity coefficient on the instantaneous wall heat flow density distribution at different moments were investigated based on the lattice Boltzmann pseudopotential model with hydrothermal coupling double distribution functions.The results show that the diffusion and dive of low-temperature droplets lead to an increase in the temperature gradient between the wall and liquid film in the impact zone and the central jet zone,causing a sharp increase in the heat flow density of the wall in the impact zone and the central jet zone.The heat transfer in the impact zone is mainly in the form of convective heat transfer,and the heat transfer in the static zone is mainly in the form of diffusive heat transfer due to the effect of velocity discontinuity at the liquid crown.The increase of double droplets impact velocity leads to the deepening of droplet dive and expansion,and the convective heat transfer inside the liquid film is enhanced.The increase of double droplets spacing causes the expansion space of the liquid crown inside the liquid film to increase,resulting in the increasing area of high heat flow density region on the transient wall surface,which is conducive to heat dissipation.In addition,the larger viscosity coefficient of the liquid phase increases the viscous dissipation during the droplet impact with the liquid film,which reduces the dive of the low-temperature droplet and the convection intensity of the liquid film flow field in the impact area,and leads to the reduction of the peak heat flow density at the wall surface.
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