论文和技术资料

Laser cutting is increasingly studied for the dismantling of end-of-life or damaged nuclear facilities due to its remote operation capability and efficiency for cutting thick metal sections in hazardous environments. One major concern of laser cutting in the nuclear industry is managing the portion of the laser energy that propagates beyond the kerf and may cause thermomechanical damage to structures behind the workpiece. To predict and control this residual energy, a detailed understanding of the thermal, fluid, and optical phenomena that occur during laser cutting is essential. Previous work developed a model in COMSOL Multiphysics® to represent the heat transfer and fluid flow phenomena in the metal and a particle tracing method to estimate the residual energy reaching the background [1], but with limiting assumptions.

In this context, present work improves the model in two directions. The first focuses on the thermal contributions of the oxidation reaction. Indeed, previous work used an inert assist gas instead of air. The improvement proposed here is done by introducing an additional volumetric heat source term associated with the formation of oxides.

The second objective focuses on a more accurate estimation of the forces exerted by the assist gas on molten metal. Existing models rely on indirect, analytical equations of the forces derived using the boundary-layer approximation for incompressible laminar flow [2] . However, for effective melt evacuation, the flow must exit the nozzle at very high velocities; often reaching supersonic regimes. To account for these effects, the compressible Reynolds-Averaged Navier–Stokes (RANS) equations are solved to directly simulate the gas flow and evaluate the forces acting at the metal-gas interface. To validate the simulation results, experimental campaigns are currently being conducted to compare the cutting front profile for different operating parameters.