油 滴 与 高 温 固 体 壁 面 碰 撞 的 动 态 铺 展 与 传 热

The lubrication and cooling states of mechanical parts under spray and drip lubrication conditions are dra⁃ matically influenced by the flow and heat transfer characteristics of the film formed by the impingement of oil droplet with parts surface. A three-dimensional numerical calculation model of the flow and heat transfer concerning a droplet impacting on a heated solid wall with the consideration of the correlation between the thermodynamic feature param ⁃ eters of oil droplet and temperature is proposed using VOF（Volume of Fluid）method to predict numerically the droplet morphology evolution，and the heat transfer between film and heated surface. The correctness of the presented model is demonstrated by comparison of the numerical results with experimental data. The effects of incident velocity，wall temperature and droplet temperature are discussed in detail. The results show that inside the center of the spreading film a lone bubble is formed by air entrapment between droplet and solid wall during the initial stages of impact，and then the bubble collapses and escapes into the air when it floats upward to the film surface. The film at the maximum spreading diameter appears to be a plate with a flat center region and a protruding rim. The drastic heat exchange oc⁃ curs in the vicinity of three-phase contact line of film，air and heated wall，so that local heat flux near the film rim is sig⁃ nificantly greater than that of other region inside the spreading film，and the phenomenon becomes more remarkably with the spreading process. The dimensionless spreading factor increases with the increase of the incident velocity and the droplet temperature，and seems to affect insignificantly by the wall temperature. The increased incident velocity and wall temperature contribute to the heat transfer between film and heated wall，so the average heat flux at the solid surface increases obviously. The radial heat flux in the film at the maximum spreading diameter increases with the inci⁃ dent velocity and the wall temperature.