Supersonic flow characteristics in laser grooving

The gas flow structure in laser grooving has been evaluated by numerical simulation and experiments in this study. A nozzle designed with a specific arrangement of compound jets for laser grooving has been tested. For this nozzle configuration the compressible flow structure of a shock wave induced by a supersonic side jet has been predicted in a numerical simulation using FLUENT, a computational fluid dynamics code and visualized in the experiment where the wall pressure on the grooving zone was evaluated and measured for jets impinging on the substrate at varying attacking angles of the side jet. The results obtained numerically and experimentally were comparable. In addition, the relationships between the material removal efficiency and the flow structure have also been established. It transpired that the attacking angle made a significant and dramatic improvement on the flow structure and grooving appearance and that a large wall pressure with a clear grooving profile can be obtained for attacking angles between 40° and 50° in the present test setup.