Laser evaporative heating in relation to machining

Abstract

Laser pulse heating and phase change process taking place in the region irradiated by a laser beam are considered. A numerical method is employed to predict the temperature field, recessing velocities of evaporating and melting surfaces. An experiment is conducted to compare the cavity size obtained from the experiment with the prediction. The predicted recession velocity of the evaporating surface is compared with the results of one-dimensional closed form solution. The influence of laser pulse intensity on the recession velocity, the size of the mushy zones and resulting cavity formation in time and its shape are computed. Heating situation is simulated through a numerical scheme employing finite difference method. The grid independent tests are carried out to secure grid independent solutions. The study is extended to include the vapor ejection from the temporally developing cavity due to evaporating surface. A numerical scheme employing a control volume approach is used in solution. The vapor jet is considered to expand into the stagnant water, which is situation observed in laser shsock processing of the surfaces. Since the actual vapor front density is not known and not provided in the open literature, two extreme densities are introduced in the simulations.