Aero-Thermal Modeling of Laser Metal Deposition with Wire (LMD-w): Development of a CFD-Based Methodology

Abstract

In Laser Metal Deposition with Wire (LMD-w), components are built layer by layer by continuously melting and depositing wire material, typically using alloys such as Ti-6Al-4V. The process involves complex interactions between heat input, build geometry, and surrounding gas flow, which determine the aero-thermal conditions in the build zone. These conditions and governing mechanisms are challenging, and the available methods are often limited in terms of calibration and validation. As a result, phenomena such as thermal accumulation and flow behavior largely rely on trial-and-error in process development. To address this limitation, a CFDbased methodology for analyzing the build zone environment is developed. Firstly, a calibration case is used to assess and validate the thermal modeling of the solid, addressing aspects such as laser heat input, phase change, and convective and radiative heat transfer, providing a basis for subsequent simulations. Secondly, the modeling assumptions established in the calibration study are applied to the real geometry to assess the suitability of simulation methods. The results suggest that steady-state modeling captures the asymptotic thermal behavior of the solid and offers a computationally efficient alternative to long transient simulations while still providing relevant temperature data. Finally, the methodology is extended to coupled conjugate heat transfer (CHT) simulations, enabling analysis of fluid-solid interaction and the thermal response of the solid under realistic flow conditions. In addition, a forced cooling strategy is investigated, where argon is injected through tubes directly onto the surface, resulting in a significant improvement in the temperature distribution of the solid. The developed methodology provides a foundation for analyzing build zone conditions and enables future studies on parameter sensitivity, cooling strategies, and process optimization.