Numerical modeling of heat transfer and fluid flow in laser metal deposition by powder injection
Abstract
Laser metal deposition is an additive manufacturing technique which allows quick fabrication of fullydense metallic components directly from Computer Aided Design (CAD) solid models. A selfconsistent threedimensional model was developed for the laser metal deposition process by powder injection, which simulates heat transfer, phase changes, and fluid flow in the melt pool. The governing equations for solid, liquid and gas phases in the calculation domain have been formulated using the continuum model. The free surface in the melt pool has been tracked by the Volume of Fluid (VOF) method, while the VOF transport equation was solved using the Piecewise Linear Interface Calculation (PLIC) method. Surface tension was modeled by taking the Continuum Surface Force (CSF) model combined with a forcebalance flow algorithm. Laserpowder interaction was modeled to account for the effects of laser power attenuation and powder temperature rise during the laser metal deposition process. The governing equations were discretized in the physical space using the finite volume method. The advection terms were approximated using the MUSCL flux limiter scheme. The fluid flow and energy equations were solved in a coupled manner. The incompressible flow equations were solved using a twostep projection method, which requires a solution of a Poisson equation for the pressure field. The discretized pressure Poisson equation was solved using the ICCG (Incomplete Cholesky Conjugate Gradient) solution technique. The energy equation was solved by an enthalpybased method. Temperaturedependent thermalphysical material properties were considered in the numerical implementation. The numerical model was validated by comparing simulations with experimental measurements.
 Publication:

Ph.D. Thesis
 Pub Date:
 2013
 Bibcode:
 2013PhDT.......161F
 Keywords:

 Engineering, Mechanical;Physics, High Temperature;Applied Mechanics;Physics, Elementary Particles and High Energy