Study On Thermal Stress Of Pipeline In Nuclear Power Plant Based On Fluid-solid Coupling

Nuclear power plant pipelines are generally metal materials,the fluid's temperature change in the pipeline,the corresponding expansion or contraction of the pipeline,the stress on the wall is alternating change,resulting in thermal fatigue damage to the pipeline with cracks,which will be develop penetrating cracks that eventually lead to failure of piping and leaks possible,which has seriously affected the safety of nuclear power plants.In view of the problem of pipeline thermal fatigue in the nuclear power plant,the topic for the pipeline in nuclear power plant thermal fatigue based on the theory of elastic thermodynamics,finite element theory and fluid-solid coupling theory,with straight pipe,elbow,T tube as the research object,the fluid-solid coupling pipeline model was established on the ANSYS Workbench software platform,under the temperature loading conditions,taking into account the flow and heat transfer of pipe fluid,the heat transfer of pipe wall,the fluid-solid coupling factor of fluid and wall interface heat transfer,the study of the stress state of pipeline.The research shows that a straight pipe,elbow,T tube under the same conditions,thermal stress distribution pipeline there is a big difference,The stress concentration occurs at the discontinuity of the pipeline structure,the most easy to produce stress concentration in the T tube,which the stress value is the largest;when cold and hot fluids mix in the T tube,Complex thermal stress stratification occurs at the intersection of the core area of main and branch,the upper wall downstream of the core area and outlet of branch,these areas where are also prone to thermal fatigue.The greater difference the temperature between the main and the branch,the greater the degree of invasion of the branch;the maximum stress value of the pipeline is affected by the average temperature than the temperature difference.The result will be beneficial to understanding of the pipeline thermal fatigue phenomenon of nuclear power plants,and has great important significance to improve the operation of the nuclear power plant safety,reliability and economy.