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Laser heating of thin cylinders
Fiber wound polymer materials are widely used in many engineering applications. As a favorite curing method, laser online curing provides the possibilities of producing high performance polymer material with less cost. The energy interaction between the laser and cylinder needs to be thoroughly investigated in order to understand the laser online curing process. ^ This study involves a theoretical and experimental investigation of the laser interaction with a cylinder. A geometrical optical model was constructed to derive the characteristics of laser transmission and absorption inside a cylinder with or without an outer layer. The results of the model indicate that the internal intensity distribution within the cylinder depends significantly upon the illuminating beam properties, layer thickness and optical properties of the cylinder. A comparison between the results of the geometrical model with the results of an exact electromagnetic model shows good agreements. The advantage of the geometrical model is that it can handle larger sized cylinders. ^ A three dimensional heat transfer model which incorporates the results from the optical model has been developed to determine the transient and steady-state temperature distribution inside a cylinder for both the stationary and moving cases. A finite difference method with a variable nodal network was employed to solve the heat transfer model. ^ An experimental system was built in order to obtain experimental data which could be used to assist in the development and validation of the theoretical model. A high power diode laser array and an optical system which collimated the highly divergent beam from the laser were involved in the experiment. The intensity distribution and the focusing of the beam were measured. Different cylinder velocities were achieved by driving an absorbing liquid through small diameter glass tubing using variable-flow peristaltic pumps. The experimental arrangement allows control of the laser power output, the diameter of the cylinder, the optical properties of the cylinder, and the velocity of the moving cylinder. ^ The temperature distribution variation was measured and then analyzed with respect to the laser power, the optical properties of the cylinder, and the velocity of the moving cylinder. The experimental and the theoretical simulation results agree well. It is found that free convection affects the flow and heat transfer if the tube diameter is relatively big or the flowrate is relatively slow. ^
Qu, Yi, "Laser heating of thin cylinders" (2004). ETD collection for University of Nebraska - Lincoln. AAI3142096.