Numerical Simulation Of Heat-fluid-solid Coupling Process In Microchannel Cooler

Thermal effect in the laser medium has become a serious obstacle to further improve in the laser output power. A new microchannel system with high cooling efficiency has emerged. Although researches on the microchannel cooling system and the thermal effect in the laser medium have been carried out by domestic and international scholars, but very few of them have considered the coupling of the temperature, flow and stress comprehensively.Heat-fluid-solid coupling is a science widely used in thermodynamics of solid research, which studies (A) the flow and heat transfer between fluid and solid, (B) the solid deformation caused by the flow and temperature, (C) the influence of the solid deformation on the flow. ANSYS Workbench developed by the ANSYS.inc is a collaborative simulation environment, which is widely used in heat-fluid-solid coupling.This research took the microchannel system in solid-state laser with double-sided cooling medium structure as the research object to study the thermal effect in the solid-state laser. Based on the established two-dimensional and three-dimensional model of the microchannel cooling system, the heat-fluid-solid coupling mechanics has been analyzed with the help of ANSYS Workbench software. Major results can be concluded as follows:The largest stress is on the edges of the solid constraint surface. The influence of the thermal deformation on the flow can be ignored. It shows that the unidirectional heat-fluid-solid coupling calculation method is reliable.Then, the following results can be found after the simulation of the microchannel cooler under different basic conditions. The results of the simulations under different dimensions aligned fairly well. The results under different Reynolds number determine that the optimal flow operating Reynolds number is Re=3000. Dynamic simulation results show that the stable temperature is the highest temperature in the fluid, and the stable time decreases with the increase of the Reynolds number. Analysis results of different heat source and cooling medium show that:the optimized operating Re is the same under different heat in the crystal. The minimum pressure requirement is higher with a greater heat in the crystal, and this effect decreases with the increase of the Reynolds number. There is significant difference of crystal temperature and the total pressure drop in the channel with different cooling medium. The difference of crystal temperature distribution is little under different kinds of heat source. Analysis result of different crystal thickness and the microchannel width shows that crystal thickness can be increased when considering the crystal temperature and the absorption of the pump power appropriately. Model can be simplified by decreasing the width properly when studying microchannel cooling system with large aspect ratio.In addition, the following results can be found after the simulation of thermal deformation and stress under different Reynolds number and crystal heat. The stress on the edges of the solid constraint surface is always the largest. It decreases with the increase of Reynolds number. Also the thermal deformation of the crystal has different distribution under different flow state. Maximum thermal deformation and stress of the crystal almost increase linearly with the increase of the heat in the crystal. Finally, the influence of the heat effect in laser medium on beam quality has been examined. The thermal deformation has a strong impact on the total optical path difference. So the thermal deformation couldn't be neglected when studying the thermal effects on beam quality.