ABSTRACT

In this study, the droplet flight path and the mass flux in the Uniform Droplet Spray Forming (UDS) process are characterized through numerical simulation and experiments. In the UDS process electrically charged uniform diameter metal droplet sprays are used to spray form deposits onto stationary and moving substrates. A numerical simulation based on physical models was developed to predict the droplet velocity, the droplet spray cone spreading, the mass flux distribution in the spray, and the cross-sectional shapes of deposits spray formed with a moving substrate. 

To verify the numerical simulation results experiments were performed to measure the droplet charging, the droplet velocity, the droplet scattering, and the deposit cross-sectional shapes. The charging and scattering experiments were performed with 200mm diameter Sn droplets. The velocity was measured as a function of flight distance for 95mm and 200mm diameter Sn droplets. The deposit cross-sections were measured for 200mm diameter Sn-40%Pb sprays collected at a flight distance of 300mm and for 200mm diameter Sn-5%Pb droplets at a flight distance of 480mm. The experimental results agreed with the simulation results to within approximately 10% for the charging, velocity, and scattering experiments. There was a larger discrepancy between the shape of cross-sectional deposits due to variations in the process and the impact behavior of the droplets. This numerical simulation can be used to predict droplet flight path and mass flux for single and multiple orifice sprays.

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