# Numerical Simulation of Liquid Film Characteristics during Atomization of Aluminum Alloy Powder
## 3 Simulation Results and Discussion
### Liquid Film Characteristics with Disk Structure at Different Speeds
In Figures 13 and 14, the continuous liquid film boundary diameters of different atomizing disks at different rotational speeds show that the continuous liquid film boundary diameter widths of flat and spherical disks gradually decrease with increases in rotational speed, and the continuous liquid film boundary diameter widths of the flat disk decrease by 28.7%, from 36.5 mm to 26 mm, when the rotational speed increases from 10,000 rpm to 30,000 rpm. The continuous liquid film boundary diameter width of the spherical disk is reduced by 32.9%, from 47 mm to 31.5 mm. When the rotational speed increases from 30,000 rpm to 60,000 rpm, the boundary diameter width of the continuous liquid film of the flat disk decreases from 26 mm to 19 mm, by approximately 25.9%, and the boundary diameter width of the continuous liquid film of the spherical disk decreases from 31.5 mm to 24.5 mm, by approximately 22.2%. By analyzing the above data, it can be concluded that the variation amplitude of the boundary diameter of different disk-shaped continuous liquid films is not notably different under the same speed variation amplitude, and the difference in the variation amplitude is less than 5%. Moreover, in Figure 15, the boundary diameters of the continuous liquid films on the flat and spherical disks at different speeds can be seen to decrease with increasing speed, and the slope and change law of the curve are almost the same, further proving that the boundary diameters of different continuous liquid films with different disk shapes are almost the same at the same speed. Therefore, it is proven that the continuous liquid film boundary diameter is most affected by the speed of the atomizing disk, while it is less affected by the disk shape. However, it can also be seen from Figure 15 that, under the same working conditions, the overall boundary diameter of the continuous liquid film of the spherical disk is approximately 21-29% larger than that of the flat disk, i.e., the shape of the disk plays a decisive role in the overall boundary diameter of the continuous liquid film, which is consistent with the characteristics of the liquid film on the flat disk and the spherical disk obtained by the VOF method. The accuracy of the result is proven. Figure 14: Cloud image of liquid film distribution on spherical disk at different rotational speeds. (a) 10,000 rpm; (b) 30,000 rpm; (c) 60,000 rpm. Figure 13: Cloud image of liquid film distribution on a flat disk at different rotational speeds. (a) 10,000 rpm; (b) 30,000 rpm; (c) 60,000 rpm. As for the distribution clouds of the liquid film on the surfaces of different disk shapes at different speeds shown in Figures 13 and 14, the comparative analysis shows that, compared with the flat disk, the thickness of the liquid film on the surface of the spherical disk is relatively uniform, and the liquid filaments are finer and greater in number. After further processing of the simulation results, the average liquid film thickness data for different speeds were obtained, as shown in Figure 16. It can be seen from Figure 16 that the average liquid film thickness on the surfaces of the flat and spherical disks gradually decreases with the increase in the rotational speed. When the rotational speed increases from 10,000 rpm to 30,000 rpm, the average thickness of the liquid film on the surface of the flat disk decreases from 14 \(\upmu\)m to 13 \(\upmu\)m, and the average thickness of the liquid film on the surface of the spherical disk decreases from 9.8 \(\upmu\)m to 9.1 \(\upmu\)m. The reduction amplitudes of the two disk shapes are almost the same, decreasing by approximately 7%. When the rotation speed increases from 30,000 rpm to 60,000 rpm, the average thickness of the liquid film on the surface of the flat disk decreases from 13 \(\upmu\)m to 8.7 \(\upmu\)m, with a decrease of 33.1%, and that of the spherical disk decreases from 9.1 \(\upmu\)m to 8.4 \(\upmu\)m, with a decrease of approximately 7.7%. The reduction amplitudes of the two disk shapes are quite different.