3-Dimensional conjugate laser heating of a moving slab

The laser surface treatment of engineering parts requires gas assisted processing, since the assisting gas shields the surface from the high temperature oxidation during the laser heating process. In the present study, modeling of the laser gas-assisted heating process is considered. The assisting gas, which is air, is assumed to impinge onto the workpiece surface co-axially with the laser beam while the workpiece, which is stainless steel, moves with a constant velocity. Low-Reynolds number k-ε model is introduced to account for the turbulence. The flow and heat conduction equations are solved numerically using a control volume approach. The simulation of a conjugate heating is carried out for three workpiece speeds. It is found that the workpiece movement effects considerably the temperature rise inside the solid substrate i.e. higher the workpiece speed results in lower the surface temperature in the direction of workpiece movement. In addition, the convective cooling effect of the impinging gas jet is more pronounced as the radial distance along the workpiece surface increases.