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Temperature Fluctuations in Fluid and Pipe Walls induced by Turbulent Mixing

English title Temperature Fluctuations in Fluid and Pipe Walls induced by Turbulent Mixing
Applicant Prasser Horst-Michael
Number 132659
Funding scheme Project funding (Div. I-III)
Research institution Institut für Energietechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Technical Physics
Start/End 01.02.2011 - 31.01.2015
Approved amount 238'857.00
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All Disciplines (2)

Discipline
Technical Physics
Fluid Dynamics

Keywords (9)

turbulent mixing; temperature fluctuations; tee junctions; thermal fatigue; RANS; temperature fluctuation transport model; wire-mesh sensors; Reynolds Averaged Navier Stokes;

Lay Summary (English)

Lead
Lay summary
Lead: Turbulent mixing of streams with different temperature may result in significant temperature fluctuations in the walls of pipes and other components of power plants or other industrial installations. These fluctuations may cause thermal fatigue in the wall material and pose the risk of a failure of the component. Method: The proposed project is focused on the prediction of temperature fluctuations in a T-junction. It is planned to apply Reynolds Averaged Navier-Stokes (RANS) modeling as an alternative to very computational expensive LES simulations. RANS modeling will be extended by temperature fluctuation transport equations. It is based on a second averaging of the scalar transport equation, which results in additional transport equations for the RMS of the temperature, and turbulent heat fluxes. This approach reduces computational costs compared to LES by orders of magnitude. Still, it is possible to obtain distributions of the RMS of the fluid temperature. For a subsequent fatigue analysis, estimates of the temperature fluctuations in the wall and their frequency range are needed. The feasibility of methods for an approximate determination of the time scale of turbulent mixing patterns found in the fluid and a simplified modeling of the response of the temperature field in the wall will be explored. For the experimental part, a co-operation with the Laboratory of Nuclear Power (IKE) of the University of Stuttgart will be established. IKE has started to construct a T-junction experiment operating parameters of an original nuclear power plant. We will construct a second test facility to perform complementary mixing experiments at room temperature respecting fluid dynamic similarity. Mesh sensor techniques provide two-dimensional distributions of the transport scalar with a time resolution of up to 10 kHz for the support of the model development. Aim: The main outcome of the project is an efficient method for the prediction of temperature fluctuations in components, where fluid streams of different temperature are mixed. This phenomenon has a relevant impact to the lifetime of components of nuclear power plants and other industrial installations. The results will therefore contribute to economy and safety of these plants. The fast-running RANS simulations aim at performing preliminary screenings of components to identify locations of critical amplitudes of temperature fluctuations, especially in complex, large-scale geometries. Locations with critical amplitudes of temperature fluctuations can be identified and a more detailed research using time-consuming LES methods or dedicated experiments can be focused to relevant cases.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Large Eddy Simulation of Turbulent Penetration in a T-junction
Kickhofel John, Prasser Horst-Michael (2014), Large Eddy Simulation of Turbulent Penetration in a T-junction, in International Congress on Advances in Nuclear Power Plants (ICAPP 2014), Charlotte, U.S.A.American Nuclear Society (ANS), La Grange Park, Illinois, USA.
The Influence of Density Stratification and T-junction Geometry on Turbulent Penetration
Kickhofel John, Trinca Cosimo, Prasser Horst-Michael (2014), The Influence of Density Stratification and T-junction Geometry on Turbulent Penetration, in International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10), Okinawa, JapanAtomic Energy Society of Japan, Tokyo (Japan).
Turbulent Penetration in T-junction Branch Lines with Leakage Flow
Kickhofel John, Prasser Horst-Michael (2014), Turbulent Penetration in T-junction Branch Lines with Leakage Flow, in Nuclear Engineering and Design, 276, 43-53.
Steady State RANS Simulations of Temperature Fluctuation in a Single Phase Turbulent Mixing
Kickhofel John, Kapulla Ralf, Fokken Juerren, Prasser Horst Michael (2012), Steady State RANS Simulations of Temperature Fluctuation in a Single Phase Turbulent Mixing, in International Congress on Advances in Nuclear Power Plants 2012, ICAPP 2012, Chicago, USAAmerican Nuclear Society, Chicago, Illinois, USA.
Turbulent Penetration as a Thermal Fatigue Problem in low Side Flow T-Junctions
Kickhofel John, Valori valentina, Prasser Horst Michael (2012), Turbulent Penetration as a Thermal Fatigue Problem in low Side Flow T-Junctions, in Nuclear Thermal Hydraulics and Safety 8 (NTHAS8) , Beppu, JapanAtomic Energy Society of Japan, Tokyo (Japan).
Wire Mesh Sensor for High Temperature High Pressure Applications
Kickhofel John, Prasser Horst-Michael, Selvam Karthick, Laurien Eckart, Huber Hermann, Wire Mesh Sensor for High Temperature High Pressure Applications, in 16th International Topical Meeting on Nuclear Reactor Thermalhydraulics (NURETH-16), Chicago, USAAmerican Nuclear Society (ANS), La Grange Park, Illinois, USA.

Collaboration

Group / person Country
Types of collaboration
Swissnuclear Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Industry/business/other use-inspired collaboration
Paul Scherrer Institut, NES, LTH Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Universität Stuttgart, IKE Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Experimental and Computational Multiphase Flow Group (NERS) Individual talk The Influence of Density Stratification and T-junction Geometry on Turbulent Penetration 10.03.2015 University of Michigan, United States of America Kickhofel John Louis;
1 day workshop at the CAMS Individual talk Turbulent Penetration as a Thermal Fatigue Problem in Nuclear Power Plants 17.11.2013 Center for Advanced Mathematical Sciences, American University of Beirut, Lebanon Kickhofel John Louis;
American Nuclear Society Summer Meeting Individual talk Pulsating Turbulent Penetration in T-junction Mixing Experiments 18.06.2013 Atlanta, GA, United States of America Kickhofel John Louis;
Thermal Hydraulics of Innovative Nuclear Systems (THINS) Cluster Workshop 2 Individual talk Turbulent Penetration in T-Junctions 07.02.2013 Royal Institute of Technology (KTH), Stockholm, Sweden Kickhofel John Louis;
Seminar INSS Japan Individual talk High Temperature and Pressure Wire Mesh Sensor 20.12.2012 Institute of Nuclear Safety System Incorporated, Fukui, Japan Kickhofel John Louis;
SwissNuclear "Tag der Forschung" Individual talk Temperature Fluctuations in Fluid and Pipe Walls induced by Turbulent Mixing 08.05.2012 Gösgen Nuclear Power Plant, Switzerland Kickhofel John Louis; Prasser Horst-Michael;


Self-organised

Title Date Place
Joint one-day workshop on two-phase instrumentation with Prof. Kikura from TokyoTech, Japan 25.08.2014 ETH Zurich, Switzerland

Awards

Title Year
Best student paper award for the conference paper: John Kickhofel, Horst-Michael Prasser, Karthick Selvam, Eckart Laurien, Hermann Huber: MESH SENSOR FOR HIGH TEMPERATURE HIGH PRESSURE APPLICATIONS. NURETH-16, Chicago, IL, August 30-September 4, 2015, proceedings p. 841. Doted financially with 500 USD. 2015

Associated projects

Number Title Start Funding scheme
141025 Turbulent Mixing of Two Gas Streams with High Density Ratio 01.09.2012 Project funding (Div. I-III)

Abstract

Turbulent mixing of streams with different temperature may cause significant temperature fluctuations in the walls of pipes and other components of power plants or other industrial installations. These fluctuations may cause thermal fatigue in the wall material and pose a risk to the safety and reliability of the plant. The proposed project is focused on the prediction of temperature fluctuations in a T-junction by techniques of experimental simulation and a contribution to the theoretical prediction for arbitrary geometries by means of an extension and validation of Reynolds Averaged Navier-Stokes (RANS) modeling. For the experimental part, a co-operation with the Laboratory of Nuclear Power (IKE) of the University of Stuttgart will be established. IKE has started to develop and construct a T-junction experiment that will provide measuring data on the velocity and temperature fields inside the flow domain at operating parameters of an original nuclear power plant for the first time. High parameters pose a number of limitations to the applicability of measuring methods. For this reason, temperature information will be obtained only at a limited number of locations by the use of thermocouples. It is therefore proposed to construct a second test facility, the test geometry of which is an identical copy of the IKE T-junction to perform mixing experiments at room temperature. Mesh sensor techniques based on detection of electrical conductivity will be used instead of thermocouples. These sensors provide two-dimensional distributions of the transport scalar at hundreds of individual measuring positions with a time resolution of up to 10 kHz and are from this point o view extremely superior to thermocouples. The temperature as transport scalar is simulated by an addition of a tracer salt that increases the electrical conductivity of the fluid. In this way, mixing patterns become visible to mesh sensors. As an alternative, it is planned to detect temperature fluctuations directly via the temperature dependency of the electrical conductivity of water, which is less accurate but opens to door to non-adiabatic tests at the cold, non-pressurized test rig. Beside flow instrumentation, the IKE T-junction is equipped with strain gauges, too. Tests will be performed until failure of the tested component, which allows mechanical testing of the fragments. It is a considerable added value of the proposed exchange of experimental results that also the data of the structural behavior will be made available to the Swiss partner. The theoretical part of the proposed PhD project aims at predicting temperature fluctuations by means of steady-state RANS simulations. This is interesting from a practical point of view: LES, which has been found to be the ideal tool to predict the temperature fluctuations, becomes too expensive when more complex and larger geometries typical for industrial plants have to be analyzed. In previous work, it has been demonstrated that solving Reynolds stress equations coupled with a transport equation for the temperature fluctuations reduce computational costs compared to LES by orders of magnitude. Still, with this technique it is possible to obtain distributions of the RMS of the fluid temperature. It is the task of the PhD student to perform numerical simulations aiming at a validation of this model and to explore possibilities for assessing the resulting temperature fluctuations in the wetted wall, as well as their characteristic frequency range.
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