Numerical analysis of heat transfer behavior of atomized droplets during high velocity arc spraying:Ⅱ Influence of process parameters on heat transfer behavior of droplets

The influences of several important process parameters on the heat transfer behavior of the atomized droplets were numerically simulated and analyzed.The results show that the process parameters such as atomizing gas pressure,spraying current and spraying distance have great influences on the heat transfer behavior of the droplet.The droplet size considerably affects the heat transfer behavior of the atomized droplet.To a certain spraying distance,decreasing droplet size will increase the convective heat transfer coefficient,temperature and cooling rate,and decrease the solid fraction.Increasing atomizing gas pressure and spraying current will increase the droplet temperature and decrease the solid fraction to a certain spraying distance,and also extend the solidification process to a larger spray distance.The droplet cooling rate are much sensitive to the droplet size and spraying distance,but insensitive to the atomizing gas pressure and spraying current.The initial cooling rates of different size droplets range from 10⁵ K/s to 10⁷ K/s,thus producing the coating microstructure with the features of rapid solidification.