Flow-Heat Transfer and Splash Characteristics of Oil Droplets Impacting onto Heated Solid Wall
Considering the dynamic changes between the oil droplet(oil film)and the contact angle of solid wall and the influence of temperature on the characteristic parameters of oil thermodynamics,a three-dimensional flow and heat transfer numerical calculation model for the impact between oil droplets and heated solid wall was established based on the volume of fluid method,and the correctness of the numerical calculation model was verified through experiments.Based on the numerical calculation model,the flow-heat transfer and splash characteristics of oil droplets and heated solid wall after impact were analyzed.Based on the experimental and numerical calculation results,the critical criterion of oil film spreading/splash was established.The results show that the state of oil droplets after impact is affected by the impact conditions.Breaking and splashing are conducive to the oil film spreading flow.Secondary oil droplets are formed by the fracture of oil bands caused by the breaking of oil film edge.The larger diameter secondary oil droplets split into small diameter oil droplets.During the spreading process of the oil film,the average heat flux on the wall increases,while the radial heat flux of the oil film gradually decreases.Increasing the impact speed,oil droplet diameter and lubricating oil temperature is conducive to the breaking and splashing of the oil film,and the number of secondary oil droplets and the lower splash angle are increased accordingly.
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