Simulation of three-dimensional laser gas-assisted heating of solid substance:

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" Simulation of three-dimensional laser gas-assisted heating of solid substance: "
S. Z. Shuja

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1113416
Doc. No	:	TLpq304479691
Main Entry	:	S. Z. Shuja
Title & Author	:	Simulation of three-dimensional laser gas-assisted heating of solid substance:\ S. Z. Shuja
College	:	King Fahd University of Petroleum and Minerals (Saudi Arabia)
Date	:	1998
student score	:	1998
Degree	:	Ph.D.
Page No	:	319
Abstract	:	The present work establishes a numerical scheme for the laser heating process with special emphasis on studying the effect, of an orthogonally impinging gas jet coaxial with the laser heated region, on the temperature distribution in the solid workpiece as well as in the gas above the workpiece. To establish a fundamental understanding, an analytical study is performed to predict the thermal response and thermal efficiency for various metals. A conjugate heating model is developed to account for the air jet impinging on a steel substrate coaxial with the laser beam and dimensions of the order of the laser heated spot. The selection of the appropriate turbulence model is accomplished through comparison of predictions obtained with the standard usd\kappa\epsilonusd and Low Reynolds Number usd\kappa\epsilonusd models, and two Reynolds stress turbulence models with the reported literature. The transient solution for the conjugate heating process is obtained numerically using the control volume approach by solving the 2-D axisymmetric form of the continuity, momentum and energy equations in consideration with the Low Reynolds number usd\kappa\epsilonusd model, provided that the effects of both constant and variable properties are considered. The simulation is extended for the repetitive pulsed laser induced heating with assisting gas jet effect with (a) a series of same intensity pulses having the same pulse length, but different cooling periods and (b) a high intensity pulse followed by a series of low intensity pulses having a constant intensity. The study is further extended to include the gas assisting single pulse laser heating of a moving workpiece through modeling the process in 3-D with variable properties. It is found that unique laser pulse parameters exist resulting in the optimum heating efficiency. The impinging gas jet velocity has no considerable effect on the heating of metal.
Subject	:	Applied sciences
	:	Fourier heat conduction
	:	Heating
	:	Laser gas-assisted
	:	Mechanical engineering
	:	Solid substance