Shift of the laser ablation center on CFRP induced by the vortex in the boundary layer of tangential airflow

The oxidation ablation of carbon fiber-reinforced polymer (CFRP) induced by a continuous wave (CW) laser under tangential airflow was modeled in this study. The fluid of the airflow and the diffusion of the oxygen in the boundary layer were simulated. The numerical predictions indicated that the center of the ablation pit deviated from the center of laser spot, which moved to the downstream area from the upstream area as the ablation time increased. These results were proven by the laser ablation experiments. The vortex appeared in the airflow when the ablation pit was deep enough. It significantly modified the mass transport of oxygen due to the recirculation in the ablation pit. Based on this model, the impacts of the airflow velocity, the laser power density, and the laser spot radius on the shift were investigated. The results of this work can be referenced for the applications of laser processing and laser damage.