Analysis of gas-powder flow in multiangle laser cladding

Multiangle laser cladding, in which the cladding head is deflected at different angles, is an advanced surface modification technology that is widely used in the repair of metal parts with complex surfaces. Nevertheless, the powder flow was affected by gravity, causing decreasing powder utilization and degrading coating quality. In this paper, to reveal the gas-powder flow mechanism, the coupled models based on the computational fluid dynamics-discrete element method (CFD-DEM) were developed. They can consider not only the continuity characteristics of gas as a fluid, the discreteness characteristics of powder as particles, but also the mutual influence relationship. Subsequently, a series of simulations and experiments were conducted in which the cladding head was deflected at angles of 0°, 30°, 60°, 90°, 120°, and 150°. The results demonstrated that with the increase in the deflection angle, the maximum powder concentration gradually declined from 16.49 to 9.80 kg m−3, the diameter of the powder spot increased progressively from 2.66 to 5.31 mm, and the powder collection rate dropped significantly from 45.11% to 27.95%. Finally, the models were experimentally validated and proved to be accurate. The findings of this research revealed the mechanism of the gas-powder flow and provided theoretical guidance for the selection and optimization of process parameters in mutiangle laser cladding.