MODELING OF LASER HEATING OF SOLID SUBSTANCE INCLUDING ASSISTING GAS IMPINGEMENT

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Abstract
Laser heat treatment finds wide application in industry because of its precision operation, its ability to be used for local heating, and its low cost. In general, an assisting gas jet is introduced coaxially with the laser beam for shielding the region treated from the oxygen. To explore the effects of the gas jet on the heating mechanism, it is essential to perform a simulation of the process. The present study is conducted to simulate three-dimensional laser heating of steel substrate when subjected to impinging gas. The gas jet is considered to impinge to the workpiece surface coaxially with the laser beam. The k-e model with and without corrections and the Reynolds stress model are tested under conditions of constant heat flux introduced from the solid wall. As a result and in accordance with previous studies, the low-Re k-ε model is selected to account for the turbulence. However, the transient Fourier heat conduction equation is considered to compute the temperature profiles in the solid substrate. A numerical method using the control volume approach is introduced to solve the governing flow and energy equations. The study is extended to include four gas jet velocities. It is found that the impinging gas jet velocity has a considerable effect on the resulting gas side temperature. Moreover, as the radial distance from the heated spot center increases, the temperature at the surface decreases rapidly. In addition, the temperature profiles inside the solid substrate are not influenced considerably by the assisting gas jet velocity.

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