Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems

Thermal fatigue cracks have been found at mixing tees in nuclear power plants. The mixing flow of high and low temperature fluids causes temperature and stress fluctuations in the pipe wall and these result in fatigue crack initiation. The authors have conducted a fluid-structure coupled simulation...

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Autores principales:	Koji MIYOSHI, Akira NAKAMURA, Yoichi UTANOHARA, Masayuki KAMAYA
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2018
Materias:	thermal fatigue mixing tee pipe temperature fluctuation thermal stress numerical simulation Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/d536e36030f640609d791b9cd7e15e92
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spelling	oai:doaj.org-article:d536e36030f640609d791b9cd7e15e922021-11-26T07:21:52ZNumerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems2187-974510.1299/mej.18-00272https://doaj.org/article/d536e36030f640609d791b9cd7e15e922018-07-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/5/4/5_18-00272/_pdf/-char/enhttps://doaj.org/toc/2187-9745Thermal fatigue cracks have been found at mixing tees in nuclear power plants. The mixing flow of high and low temperature fluids causes temperature and stress fluctuations in the pipe wall and these result in fatigue crack initiation. The authors have conducted a fluid-structure coupled simulation to estimate the fluid and pipe wall temperatures in a mixing tee in their previous study. In the present study, the authors simulated thermal stress using the previous simulation results of the pipe wall temperature. The simulated thermal stress was validated using the stress obtained from the temperature on the pipe inner surface measured by mock-up tests. The test section of the tee pipe was made of stainless steel and consisted of a horizontal main pipe with a diameter of 150 mm and a T-junction connected to a vertical pipe with a diameter of 50 mm. The ranges of the large temperature and stress fluctuation areas on the pipe inner surface calculated by the fluid-structure coupled simulation were narrower in the axial direction of main pipe compared with the results of test. On the other hand, the profiles of the circumferential direction were reproduced by the fluid-structure coupled simulation. The maximum values of the temperature and stress fluctuation ranges were overestimated. The stress fluctuation obtained from the measured temperature showed the equibiaxial behavior where the axial and circumferential stresses had a proportional relationship. Such characteristics of stress fluctuation were reproduced well by the numerical simulation. Not only the stress fluctuation range but also the number of cycles for the stress amplitude were estimated using the time history of the thermal stress and the rain-flow counting method. The distribution of the number of cycles for the stress amplitude estimated by the simulation was similar to that obtained from the measured temperatures.Koji MIYOSHIAkira NAKAMURAYoichi UTANOHARAMasayuki KAMAYAThe Japan Society of Mechanical Engineersarticlethermal fatiguemixing tee pipetemperature fluctuationthermal stressnumerical simulationMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 5, Iss 4, Pp 18-00272-18-00272 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	thermal fatigue mixing tee pipe temperature fluctuation thermal stress numerical simulation Mechanical engineering and machinery TJ1-1570
spellingShingle	thermal fatigue mixing tee pipe temperature fluctuation thermal stress numerical simulation Mechanical engineering and machinery TJ1-1570 Koji MIYOSHI Akira NAKAMURA Yoichi UTANOHARA Masayuki KAMAYA Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
description	Thermal fatigue cracks have been found at mixing tees in nuclear power plants. The mixing flow of high and low temperature fluids causes temperature and stress fluctuations in the pipe wall and these result in fatigue crack initiation. The authors have conducted a fluid-structure coupled simulation to estimate the fluid and pipe wall temperatures in a mixing tee in their previous study. In the present study, the authors simulated thermal stress using the previous simulation results of the pipe wall temperature. The simulated thermal stress was validated using the stress obtained from the temperature on the pipe inner surface measured by mock-up tests. The test section of the tee pipe was made of stainless steel and consisted of a horizontal main pipe with a diameter of 150 mm and a T-junction connected to a vertical pipe with a diameter of 50 mm. The ranges of the large temperature and stress fluctuation areas on the pipe inner surface calculated by the fluid-structure coupled simulation were narrower in the axial direction of main pipe compared with the results of test. On the other hand, the profiles of the circumferential direction were reproduced by the fluid-structure coupled simulation. The maximum values of the temperature and stress fluctuation ranges were overestimated. The stress fluctuation obtained from the measured temperature showed the equibiaxial behavior where the axial and circumferential stresses had a proportional relationship. Such characteristics of stress fluctuation were reproduced well by the numerical simulation. Not only the stress fluctuation range but also the number of cycles for the stress amplitude were estimated using the time history of the thermal stress and the rain-flow counting method. The distribution of the number of cycles for the stress amplitude estimated by the simulation was similar to that obtained from the measured temperatures.
format	article
author	Koji MIYOSHI Akira NAKAMURA Yoichi UTANOHARA Masayuki KAMAYA
author_facet	Koji MIYOSHI Akira NAKAMURA Yoichi UTANOHARA Masayuki KAMAYA
author_sort	Koji MIYOSHI
title	Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
title_short	Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
title_full	Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
title_fullStr	Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
title_full_unstemmed	Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
title_sort	numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems
publisher	The Japan Society of Mechanical Engineers
publishDate	2018
url	https://doaj.org/article/d536e36030f640609d791b9cd7e15e92
work_keys_str_mv	AT kojimiyoshi numericalsimulationofthermalstressfluctuationatamixingteeforthermalfatigueproblems AT akiranakamura numericalsimulationofthermalstressfluctuationatamixingteeforthermalfatigueproblems AT yoichiutanohara numericalsimulationofthermalstressfluctuationatamixingteeforthermalfatigueproblems AT masayukikamaya numericalsimulationofthermalstressfluctuationatamixingteeforthermalfatigueproblems
_version_	1718409685980151808

Numerical simulation of thermal stress fluctuation at a mixing tee for thermal fatigue problems

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