By refining the mesh convergence of the DMD laser cladding nozzle model, the simulation accuracy is improved

Through the previous computational simulation analysis, it was found that the focal point of the printing powder was not always located on the axis of the nozzle model. Combined with the analysis of the simulation results, Anshi Asia-Pacific has ruled out the influence of the asymmetry of the design of the nozzle itself and the asymmetry of gravity on the deviation of the powder focus and the geometric center of gravity. After a series of engineering judgments, it is preliminarily guessed that the asymmetry is caused by numerical influencing factors. By analyzing the deviation of results caused by the limitations of numerical processing methods in the process of model making, we will explore how to improve the accuracy of the simulation.

This paper focuses on DMD laser cladding3D printingA series of problems found in the research and development stage of the model were investigated, and it was determined that the quality of the mesh may be an important reason for the difference between the calculation results and the physical experiments and empirical analysis. Through a series of mesh convergence studies, the relatively optimal mesh structure is selected to improve the simulation ability.

Validation and Hypothesis

In order to ensure the symmetry of the geometric model, especially the symmetry of the powder feeding port with respect to the central axis of the nozzle. Anshi Asia-Pacific firstly analyzed the geometric model of the nozzle. In Figure 1, the axes of the three powder feed ports are extended to intersect. It can be seen from observation that this intersection is located on the central axis of the nozzle. Therefore, Anshi Asia Pacific can judge that the geometry of the powder feed port is symmetrical with respect to the central axis of the nozzle.

Figure 1 Explanation of the symmetry of the nozzle structure

In order to ensure the quality of the grid, the grid situation of the focal plane is now analyzed, and the grid size here is compared with the offset size, and the result is shown in Figure 2. Figure 2a and Figure 2b show the powder concentration nephogram and velocity nephogram at the focal plane, respectively.The two figures indicate the grid size and shape of the plane respectively.