Simulation Research On The Gas Flow Field And The Atomization Process Based On Double-decker Atomizer Designed

Spray forming, which has been widely used in the field of material formingand machining, is a rapidly solidified material-preparation technology.Atomization process is the key of spray forming. The atomizer plays animportant role in the process of atomization, which can not only make the moltenmetal obtain high energy and high speed, but also affect atomization efficiency,atomization range, atomization quality and stability and determine the propertiesof deposits.This paper designs a new double-decker composite atomizer. It consists ofthe upper constrained atomizer and the lower open atomizer. The baffle is addedto the air chamber, in order to avoid the inequality of the pressure and the gasvelocity caused by one-way inlet and double inlet.This paper firstly explores influence of the new double-decker compositeatomizer’s structures and process parameters on the gas flow field, and definesthe best structures and process parameters of the new double-decker compositeatomizer by using Fluent to simulate the states of the flow field. Then, itsimulates and analyzes primary atomization, secondary atomization and themotion of atomized droplet in the flow field by Fluent, so that we can understandthe broken mechanism of liquid column and droplet in atomization in depth.Finally, it readjusts the simulation results by water spray experimentsThrough the contrastive analysis of the flow field in different condition，itis showed that the best structure parameters of the new double-decker compositeatomizer are as follows: The upper atomizer outlet Angle is30°, the center-holediameter of the lower atomizer is60mm, the outlet Angle is60°, and the lower atomizer outlet is5mm higher than the melt delivery tube. On the condition thatthe atomizing pressure of the upper atomizer is0.4MPa, and the atomizingpressure of the lower atomizer is2.0MPa, the flow field is steady.Through analyzing the atomization process and observing the motion ofatomized droplet, it is arrived at that in the primary atomization, as the speed ofthe upper atomization gas increases, the breakup pattern of liquid columntransforms from wave breakup to liquid-sheet breakup. In the secondaryatomization, as We increases, the droplet is broken more easily. And the motionof atomized droplet is affected by its kinetic energy; the flow field has lessinfluence on the droplet with more momentum.Readjusting the simulation results by water spray experiments, the resultsshow that the work performance of the double-decker composite atomizer is good,the characteristics of the flow field with the different structures and pressure arebasically the same with the simulation results. It shows that the new double-decker composite atomizer can be applied to the spray forming.