Simulation Of Coolant Flow And Heat Transfer And Structural Optimization On Cryogenic Components For ITER Superconducting Feeder

The Coil Terminal Box(CTB), Which is belong to superconducting feeder system of ITER device, is therefore designed for housing the cold-warm transitions with the HTS current leads and the cryo-control valves for regulating the liquid helium supply to the coils and feeder busbars. An internal thermal radiation shield covers all inner surfaces of the CTB, which is help for blocking the heat radiation effect from room temperature box to low temperature parts. This dissertation mainly makes80K thermal radiation shield as the research object. By using pipeline leakage model and numerical simulation method, the paper has set up pipeline crack leakage numerical model to explain pipeline leakage characteristics. The second step, with Fluid-structure interaction method, it can make flow field and stress assessment under90°bend of different curvature radius, and achieve the optimal design of pipeline structure.First. Through analysis on the process of gas pipeline’s dynamic leakage, the calculating model of helium leakage ratio has been established. Using FLUENT to establish the pipeline helium leak model and put forward to the cryogenic helium leak numerical simulation,and calculate the transient leakage of the helium in3s. The velocity distribution, pressure curve and temperature distribution are numerical investigated. In this part, two factors were selected to study, such as the initial pipeline pressure and the distance of pipeline crack. The comparison of the numerical results to the theoretical value shows that the agreement is reasonably well. Based on the simulated results, the laws of gas leakage were optimized for diagnosis of helium leakage.According to operational characteristics of the thermal shield. The theoretical maximum temperature of thermal shield surface and the80K helium flow rates through theoretical heat load was calculated. The quality and layout of thermal shield cold pipeline directly affect safety run. The thermal shield cooling circuit flow field is analyzed by using CFD theory in dissertation. The fluid velocity distribution, pressure distribution and impact wear distribution are obtained under turbulent flow. It reveals that flow field will suddenly change and the fluid will hit the tube wall. Therefore, it is necessary to research the stress and the deformation in the tube wall with the fluid-structure interaction analysis in the pipe bend. The numerical result proved that the inside wall of the bend section is in danger when the fluid flow around the bend section. Through numerical experiments, large curvature radius can effectively improve the part stress in the pipe bend. At last, the temperature distribution of the thermal shield is investigated using numerical simulation method, the analysis results that the high surface temperature is lower than theoretical values and the optimized thermal shield is conform to actual design requirement.