Conjugate heat transfer les of thermal mixing in a T-junction

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)

Abstract

Turbulent mixing of hot and cold fluids may lead to high-cycle thermal fatigue in piping of nuclear power plants. In this work, the mixing in a T-junction experiment is studied by large-eddy simulation (LES). Conjugate heat transfer (CHT) between fluid and pipe wall is studied by replacing the plexiglass pipe of the experiment with a steel one. Different inlet and wall boundary conditions are first considered. Steady and turbulent inlets are compared, as well as adiabatic and CHT wall conditions. The turbulent inlets are created by using the vortex method which is validated for fully developed flow. The inlets are shown to have only small effect in bulk of the flow, but non-negligible effect near walls. The adiabatic and CHT cases show practically no difference in the logarithmic layer and upward, whereas near walls the difference becomes significant due to thermal inertia of the pipe wall. In bulk of the flow, the mean and fluctuating quantities show good agreement with the experiment. CHT simulations by using different meshes and flow velocities are then considered. A coarse mesh is found to yield qualitative agreement but significant errors in e.g. Reynolds stresses near walls. Temperature fluctuation intensity at the pipe inner surface is fairly similar for both meshes. Normalized profiles and spectra for different velocities are qualitatively similar, but some differences exist e.g. in distributions of wall temperature fluctuation intensity
Original languageEnglish
Pages (from-to)483-496
JournalNuclear Engineering and Design
Volume273
DOIs
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

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heat transfer
Pipe
Heat transfer
pipe
mesh
Thermal fatigue
Fluids
Steel
Experiments
Large eddy simulation
Polymethyl Methacrylate
Flow velocity
Nuclear power plants
Vortex flow
thermal fatigue
Boundary conditions
turbulent mixing
fluids
nuclear power plants
wall temperature

Keywords

  • CFD
  • conjugate heat transfer
  • LES
  • thermal fatigue
  • turbulent mixing

Cite this

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title = "Conjugate heat transfer les of thermal mixing in a T-junction",
abstract = "Turbulent mixing of hot and cold fluids may lead to high-cycle thermal fatigue in piping of nuclear power plants. In this work, the mixing in a T-junction experiment is studied by large-eddy simulation (LES). Conjugate heat transfer (CHT) between fluid and pipe wall is studied by replacing the plexiglass pipe of the experiment with a steel one. Different inlet and wall boundary conditions are first considered. Steady and turbulent inlets are compared, as well as adiabatic and CHT wall conditions. The turbulent inlets are created by using the vortex method which is validated for fully developed flow. The inlets are shown to have only small effect in bulk of the flow, but non-negligible effect near walls. The adiabatic and CHT cases show practically no difference in the logarithmic layer and upward, whereas near walls the difference becomes significant due to thermal inertia of the pipe wall. In bulk of the flow, the mean and fluctuating quantities show good agreement with the experiment. CHT simulations by using different meshes and flow velocities are then considered. A coarse mesh is found to yield qualitative agreement but significant errors in e.g. Reynolds stresses near walls. Temperature fluctuation intensity at the pipe inner surface is fairly similar for both meshes. Normalized profiles and spectra for different velocities are qualitatively similar, but some differences exist e.g. in distributions of wall temperature fluctuation intensity",
keywords = "CFD, conjugate heat transfer, LES, thermal fatigue, turbulent mixing",
author = "Antti Timperi",
note = "Project code: 77509",
year = "2014",
doi = "10.1016/j.nucengdes.2014.02.031",
language = "English",
volume = "273",
pages = "483--496",
journal = "Nuclear Engineering and Design",
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}

Conjugate heat transfer les of thermal mixing in a T-junction. / Timperi, Antti.

In: Nuclear Engineering and Design, Vol. 273, 2014, p. 483-496.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Conjugate heat transfer les of thermal mixing in a T-junction

AU - Timperi, Antti

N1 - Project code: 77509

PY - 2014

Y1 - 2014

N2 - Turbulent mixing of hot and cold fluids may lead to high-cycle thermal fatigue in piping of nuclear power plants. In this work, the mixing in a T-junction experiment is studied by large-eddy simulation (LES). Conjugate heat transfer (CHT) between fluid and pipe wall is studied by replacing the plexiglass pipe of the experiment with a steel one. Different inlet and wall boundary conditions are first considered. Steady and turbulent inlets are compared, as well as adiabatic and CHT wall conditions. The turbulent inlets are created by using the vortex method which is validated for fully developed flow. The inlets are shown to have only small effect in bulk of the flow, but non-negligible effect near walls. The adiabatic and CHT cases show practically no difference in the logarithmic layer and upward, whereas near walls the difference becomes significant due to thermal inertia of the pipe wall. In bulk of the flow, the mean and fluctuating quantities show good agreement with the experiment. CHT simulations by using different meshes and flow velocities are then considered. A coarse mesh is found to yield qualitative agreement but significant errors in e.g. Reynolds stresses near walls. Temperature fluctuation intensity at the pipe inner surface is fairly similar for both meshes. Normalized profiles and spectra for different velocities are qualitatively similar, but some differences exist e.g. in distributions of wall temperature fluctuation intensity

AB - Turbulent mixing of hot and cold fluids may lead to high-cycle thermal fatigue in piping of nuclear power plants. In this work, the mixing in a T-junction experiment is studied by large-eddy simulation (LES). Conjugate heat transfer (CHT) between fluid and pipe wall is studied by replacing the plexiglass pipe of the experiment with a steel one. Different inlet and wall boundary conditions are first considered. Steady and turbulent inlets are compared, as well as adiabatic and CHT wall conditions. The turbulent inlets are created by using the vortex method which is validated for fully developed flow. The inlets are shown to have only small effect in bulk of the flow, but non-negligible effect near walls. The adiabatic and CHT cases show practically no difference in the logarithmic layer and upward, whereas near walls the difference becomes significant due to thermal inertia of the pipe wall. In bulk of the flow, the mean and fluctuating quantities show good agreement with the experiment. CHT simulations by using different meshes and flow velocities are then considered. A coarse mesh is found to yield qualitative agreement but significant errors in e.g. Reynolds stresses near walls. Temperature fluctuation intensity at the pipe inner surface is fairly similar for both meshes. Normalized profiles and spectra for different velocities are qualitatively similar, but some differences exist e.g. in distributions of wall temperature fluctuation intensity

KW - CFD

KW - conjugate heat transfer

KW - LES

KW - thermal fatigue

KW - turbulent mixing

U2 - 10.1016/j.nucengdes.2014.02.031

DO - 10.1016/j.nucengdes.2014.02.031

M3 - Article

VL - 273

SP - 483

EP - 496

JO - Nuclear Engineering and Design

JF - Nuclear Engineering and Design

SN - 0029-5493

ER -