关键词: 激光增材再制造, 基体形态, 粉流场, 气固两相流

Abstract: The reflection of gas-powder impinging on the substrate surface was an important factor to affect the forming quality and efficiency for laser additive remanufacturing. Due to the various substrate shapes, the changes of the powder flow field were different after the powder impinging on the substrates. Gas-solid two-phase flow was taken as the theoretical basis, coupled simulation of EDEM and FLUENT software was used to study the gas-powder flow field distribution characteristics under three kinds of substrate changes, namely, regular substrate boundary, thin-wall substrate thickness and globoidal substrate curvature, and experimental verification was carried out. Results show that the turbulence of the gas field in the contact areas with the substrate increases as the nozzle is far away from the boundary, and the low-speed areas as well as the negative pressure range decreases. Meanwhile, the number of effective particles decrease exponentially. The gas field developes to the both sides obviously and the concentration of the machining centers decreases gradually with the increase of the thin-walled substrate width. And the powder flow rate in the effective ranges increases first and then remains. With the increase of the absolute curvature of substrates, the radial concentration of the convex substrate increases, and the focus range decreases, and the powder flow has a better convergence than that of concave substrates.

Key words: laser additive remanufacturing, substrate morphology, powder flow field, gas-solid two phase flow