MODELING OF LASER-HEATING OF SOLID SUBSTANCE INCLUDING ASSISTING GAS IMPINGEMENT

Laser heat treatment finds wide application in industry because of its precision operation, its ability to be used for local heating, and it s low cost. Pn general, an assisting gas jet is introduced coaxially w ith the laser beam for shielding the region treated from the oxygen. T o explore the effects of the gas jet on the heating mechanism, it is e ssential to perform a simulation of the process. The present study is conducted to simulate three-dimensional laser heating of steel substra te when subjected to impinging gas. The gas jet is considered to impin ge to the workpiece surface coaxially with the laser beam. The k-epsil on model with and without corrections and the Reynolds stress model ar e tested under conditions of constant heat flux introduced from the so lid wall. As a result and in accordance,vith previous studies, the low -Re k-epsilon model is selected to account for the turbulence. However , the transient Fourier heat conduction equation is considered to comp ute the temperature profiles in the solid substrate. A numerical metho d using the control volume approach is introduced to solve the governi ng flow and energy equations. The study is extended to include four ga s jet velocities. It is found that the impinging gas jet velocity has a considerable effect on the resulting gas side temperature. Moreover, as Be radial distance from the heated spot center increases, the temp erature at the surface decreases rapidly. In addition, the temperature profiles inside the solid substrate are not influenced considerably b y the assisting gas jet velocity.