Research On Key Problems In The Design Of SSRF High-heat-load Components

Shanghai Synchrotron Radiation Facility(SSRF) is a high performance third-generation of synchrotron radiation light source with an electron storage ring capacity of 3.5Gev,next only to SPring-8 of Japan,APS of USA and ESRF of the European Community.Up to now,SSRF is the biggest scientific platform for science research and technology development in China.The high heat load components on the front end are key components for dealing the high heat load of synchrotron radiation, as well as providing thermal protection to other components.The high heat load problems,resulting from the extremely high radiation power and peak power density in the third generation synchrotron radiation,bring new challenges to the design of SSRF front end that were never encountered in the previous two generations.This dissertation is a part of two research projects on the high heat load of the front end we are working for SSRF,it focuses on some major mechanics issues of the high heat load components in the front end,which includes heat transfer coefficient simulation on coolant tube,decreasing heat flux with grazing incidence structure,and establishing new design criteria for high heat load components.The heat transfer coefficient and flow resistance characteristics of forced convection in coolant tube are critical parameters to the design of front end components,because they influence significantly on the temperature and thermal stress distribution there.Much experimental investigation for enhancing heat transfer coefficient has been carried out at APS and SPring-8.In order to reduce study cost and time,numerical simulation is employed to assist the study on fluid flow and heat transfer in the coolant tube at SSRF,whose results show that the heat transfer coefficient and coolant water flow capacity can meet the SSRF design criteria,and the flow resistance mainly comes from the orthogonal region.The use of circular connecting tube can significantly reduce the flow resistance and increase the heat transfer coefficient of the coolant tube.In order to verify the results of the numerical simulation,an experimental system that can measure heat transfer coefficient of the tube is designed.The experimental results are in good agreement with numerical results,which implies that the use of numerical simulation of tube heat transfer is correct and feasible.The high heat load generated by the third-generation synchrotron radiation device will result in extremely high temperature and thermal stress on the surface of the high heat load components in the front end.The safety and effectiveness of the front end are influenced greatly by its components layout.While studying the temperature and stress field distributions of the synchrotron radiation heat load components,the finite element method(FEM) is used to analyze the influence of beam shift on the highest temperature and maximum stress.FEM results showed that, compared with the preliminary design of vertical grazing incidence,the horizontal grazing incidence design could reduce obviously the temperature and stress level,and the front end component in the current design of SSRF can run safely under a beam current of 300mA.In order to design components that can withstand higher heat load,we need to learn the mechanical parameters under various temperatures of the material of the front end components,Glidcop.The temperature dependent variations of several thermal properties of this material,e.g.,heat capacity,heat conduction coefficient and thermal expansion coefficient are obtained through literature study,which reveals that the mechanical properties of Glidcop is related with its shape,size and thermal treatment process,though there is so few literature reports on the stress-strain relationship under high temperature and low cycle fatigue of this material.A material testing system,MTS is employed in this research to carry out systematic study on the tensile properties of Glidcop under various temperatures,and the relationship between the overall strain and fatigue life with temperature influences is established.Detailed analysis on the temperature and stress-strain distributions were carried out with elastic-plastic finite element method in this thesis for the thermal-fatigue components used at APS under cycled load-unload synchrotron radiation and the components' temporal evolution of stress and strain was obtained.Besides,the possible destruction surface and fatigue life of the high heat load components under multiple heat loads are predicted with multi-axial low cycle fatigue(LCF) critical plane analysis.The fatigue life analysis on the SSRF high heat load components indicates that these components can be safely subjected to the cycle heat load of the synchrotron radiation under 400mA beam current.By referencing to the ASME design standards of pressure vessels,a new design criteria based on LCF life was established for the front end components.