Laser Target Thermal Effect In Water

With the rapid development of underwater laser processing, the research of laser interaction with the target underwater has attracted people's much more attention.The energy conservation law, Fourier's Law, temperature field in heat transfer and thermal conductivity differential equations and boundary conditions have been described, and the theory of laser interaction with materials in air including the target materials' absorption, reflection and conversion to laser been introduced, and the temperature field of laser heating solid materials and its melting process, the impelling speed of the solid-liquid interface, and the mass-transfer of liquids' state have been discussed respectively. On this basis, the theoretical analysis and numerical simulation study have been made for the heating process during the high-power laser interaction with the target underwater.Based on the heat conduction equation, the change of the optical and thermal physical properties of the target under laser irradiation has been analyzed, and a reasonable mathematical and physical model has been established. The transient temperature distribution of laser interaction with target underwater by using the finite element method has been gotten. By changing the different laser parameters, the images of temperature variations with time in the center of aluminum target and the images of temperature distribution of aluminum target along the axial and radial have been gotten. The calculation results have shown that the temperature field of the aluminum target distributed in a small local region, where great temperature gradient exists quite unevenly Moreover, in the same condition, the changes of temperature rise at the center of the target were studied when the target are placed in air and water respectively, and concluded the temperature rise of the target underwater when heated by laser range significantly lower than that in air.The research results can provide a theoretical basis for the selection of laser parameters underwater laser processing.