Numerical analysis of heat transfer behavior of atomized droplets during high velocity arc spraying:I.mathematical model and vari-ations of heat transfer parameters

The hish velocity arc spraying(HVAS) process relates to very complicated heat transfer behavior.And the microstructure with rapid solidification of the coating is mainly determined by the heat transfer behavior of the droplets during atomization.The heat transfer model of atomized droplets during HVAS was developed based on the theory of fluid mechanics,solidification,and Newton cooling.And the model was solved by a numerical method using a Fe-A1 alloy to analyze the variations of the heat transfer parameters with spraying distance.Experiments were carried out to measure the changes of the average temperature of atomized droplets using Spray Watch-2ion-line thermal spraying monitor system.A good agreement between the numerical and experimental results was ob-served.The results showed that the heat transfer parameters such as convective heat transfer coefficient,temperature,solid fraction and cooling rate changed in regularity.The initial cooling rate of Fe-A1 alloy droplet was about 2.5 x 106K/s,reflecting the features of rapid solidification process.