Modeling the laser-polymer interaction of laser propulsion systems considering progressive surface removal, thermal decomposition and non-Fourier effect

Abstract

During the laser-polymer interactions of laser propulsion systems, the surface of the target progressively recedes, which in turn necessitates accounting for the moving front boundary, and the decomposition rate varies with the temperature resolution, which accordingly updates the internal heat flux. The non-Fourier effect existing in ultra-short pulse laser heating also needs to account for the finite propagation speed of the thermal wave. Therefore, developing an accurate predictive simulation model that captures materials moving front, simultaneously updates the internal heat source, and characterizes the non-Fourier effect is an important and challenging task. In this study, a mathematical model of the laser-polymer interaction was numerically implemented using a two-dimensional finite volume method considering progressive surface removal, thermal decomposition, and non-Fourier effect. The proposed model utilizes a robust coupling scheme that enables us to track the moving boundary condition owing to the progressive surface material removal, simultaneously updates the internal heat source by varying the pyrolysis rate, and re-meshes the computational domain after the material surface is progressively removed. Moreover, the thermal relaxation time is introduced into the heat conduction equation to characterize the non-Fourier effect. In addition, the temperature-dependent material and optical properties of the target material were considered in the proposed model. Simulations were performed for the laser ablation of polyoxymethylene with a carbon dioxide laser under different parameters. The theoretical estimations of the ablation depths and area mass densities agree well with the experimental results.