Laser heating: jet emanating from laser induced cavity

Laser heating of steel surface and cavity formation during laser irradiation pulse are investigated. The recession of the solid surface due to melting and evaporation is modeled using an energy method. Jet emerging from the laser induced cavity and expanding into stagnant water, resembling laser shock processing, is also simulated. Governing flow equations are solved numerically using a control volume approach employing a moving mesh in the solution domain. This is because of the recessing surfaces of the vapor, liquid and solid phases during the heating pulse. It is found that mushy zone size at liquid-vapor interface is larger than that of at solid-liquid interface. Expansion of the vapor jet, emanating from the cavity and expanding into stagnant water ambient, is high in the axial direction in the early heating period, and as the time progresses the radial expansion of the jet becomes visible due to pressure build up in the jet frontal area. Considerably high recoil pressure is developed in the cavity due to high recession velocity of cavity surface and expansion velocity of vapor jet. (C) 2006 Elsevier Masson SAS. All rights reserved.