| Abstrakt: |
The ultrasonic melt treatment (UMT) is widely used in the fields of casting and metallurgy. However, there are certain drawbacks associated with the conventional process of single-source ultrasonic (SSU) treatment, such as the fast attenuation of energy and limited range of effectiveness. In this study, the propagation models of SSU and four-source ultrasonic (FSU) in Al melt were respectively established, and the distribution patterns of acoustic and streaming field during the ultrasonic treatment process were investigated by numerical simulation and physical experiments. The simulated results show that the effective cavitation zone is mainly located in a small spherical region surrounding the end of ultrasonic horn during the SSU treatment process. When the FSU is applied, the effective cavitation zone is obviously expanded in the melt. It increases at first and then decreases with increasing the vibration-source spacing (Lv) from 30 mm to 100 mm. Especially, when the Lv is 80 mm, the area of effective cavitation zone reaches the largest, indicating the best effect of cavitation. Moreover, the acoustic streaming level and flow pattern in the melt also change with the increase of Lv. When the Lv is 80 mm, both the average flow rate and maximum flow rate of the melt reach the highest, and the flow structure is more stable and uniform, with the typical morphological characteristics of angular vortex, thus significantly expanding the range of acoustic streaming. The accuracy of the simulation results was verified by physical experiments of glycerol aqueous solution and tracer particles. [ABSTRACT FROM AUTHOR] |
