wp4: safety and performance for innovative reactor systems 3 rd annual meeting, imperial college...
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WP4: Safety and Performance for Innovative Reactor Systems
3rd Annual Meeting, Imperial College London, 9th April 2008
Reynolds-Averaged Navier-Stokes (RANS) investigation of Advanced Gas-Cooled Reactors
(AGRs)
by
Amir Keshmiri
School of Mechanical, Aerospace & Civil Engineering (MACE)The University of Manchester
Manchester M60 1QD
OutlineOutline
• Topic 1: Ascending Flow in a Heated Pipe under Post-trip Condition
• Topic 2: Modelling the Coolant in the AGR’s Fuel Elements
• Topic 3: Development of Wall Functions
• Future Work
Topic 1:Topic 1:
Ascending Flow in a Heated Pipe under Post-trip
Condition
Solution MethodsSolution Methods
• In-House Code (CONVERT)In-House Code (CONVERT)
• Commercial CFD Package (STAR-CD)Commercial CFD Package (STAR-CD)
• Industrial Code (Code_Saturne)Industrial Code (Code_Saturne)
• or
• Radius=0.1 m
• Ascending Flow
• Constant Heat Flux BC
• ‘Boussinesq’ Approximation
180Reτ 5300ReD
Key Features of the Flow ProblemKey Features of the Flow Problem
The analysis focuses on 4 cases:
• Gr/Re^2=0.000 Forced Convection
• Gr/Re^2=0.063 Early onset Mixed Convection
• Gr/Re^2=0.087 Laminarization
• Gr/Re^2=0.241 Recovery
Test CasesTest Cases
Models TestedModels Tested
Turbulence Models/Techniques Tested:
• Launder-Sharma k-ε model (CONVERT)• Cotton-Ismael k-ε-S model (CONVERT)• Chen k-ε model (STAR-CD)• Suga NLEVM (CONVERT)• k-ω-SST model (Code_Saturne and STAR-CD)• Lien-Durbin v2f model (Code_Saturne and STAR-CD)• Manchester v2f model (Code_Saturne)• LES (STAR-CD) – presented by Dr. Yacine Addad
The Results are validated against:
• DNS of You et al (2003)
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Launder & Sharma Model Cotton & Ismael Model Suga ModelData of Carr et al (1973)DNS of You et al (2003) Launder & Sharma Model (Desc. flow)Cotton & Ismael Model (Desc. flow)Suga Model (Desc. flow)Data of Easby (1978) (Desc. flow)Data of Parlatan et al (1996) (Desc. flow)DNS of You et al (2003) (Desc. flow)
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Launder & Sharma Model (CONVERT)Large Eddy Simulation (STAR-CD)Data of Steiner (1971)Data of Carr et al (1973)Data of Parlatan et al (1996)DNS - You et al (2003)
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Nu
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Launder & Sharma Model (CONVERT)
Suga Non-Linear Eddy Viscosity Model (CONVERT)
k-omega-SST Model (STAR-CD)
k-omega-SST Model (Code_Saturne)
Large Eddy Simulation (STAR-CD)
DNS - You et al (2003)
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Nu
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Launder & Sharma Model (CONVERT)
k-omega-SST Model (STAR-CD)
Lien & Durbin v2f Model (STAR-CD)
Manchester v2f Model (Code_Saturne)
Large Eddy Simulation (STAR-CD)
DNS - You et al (2003)
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Bo
Nu
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Launder & Sharma Model (CONVERT)Cotton & Ismael Model (CONVERT)Suga Non-Linear Eddy Viscosity Model (CONVERT)Lien-Chen-Leschziner k-eps Model (STAR-CD)k-omega-SST Model (STAR-CD)Lien & Durbin v2f Model (STAR-CD)k-omega-SST Model (Code_Saturne)Manchester v2f Model (Code_Saturne)Large Eddy Simulation (STAR-CD)DNS - You et al (2003)
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Bo
Nu
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Launder & Sharma Model (CONVERT)Cotton & Ismael Model (CONVERT)Suga Non-Linear Eddy Viscosity Model (CONVERT)Lien-Chen-Leschziner k-eps Model (STAR-CD)k-omega-SST Model (STAR-CD)Lien & Durbin v2f Model (STAR-CD)k-omega-SST Model (Code_Saturne)Manchester v2f Model (Code_Saturne)Large Eddy Simulation (STAR-CD)DNS - You et al (2003)
Topic 2:Topic 2:
Modelling the Coolant in the AGR’s Fuel Elements
Advanced Gas-Cooled Reactors (AGRs)Advanced Gas-Cooled Reactors (AGRs)
1. Charge tubes2. Control rods3. Graphite moderator4. Fuel assemblies5. Concrete pressure vessel and radiation shielding6. Gas circulator7. Water8. Water circulator9. Heat exchanger10. Steam
Fuel ElementFuel Element
Axis of symmetry
Transverse Ribs
Work in progress:Work in progress:
Multi-Start Rib-Roughened Fuel Elements
Helical/Spiral Ribs
Topic 3:Topic 3:
Development of Development of Wall Functions
Wall FunctionsWall Functions
Standard Wall Function • Assume ‘universal’ logarithmic velocity and temperature profiles in evaluation of
wall shear stress, turbulent kinetic energy production and wall temperature.• Inaccurate results when flow departs from a state of local equilibrium.• Different versions of this WF are available in STAR-CD, Code_Saturne, TEAM
and STREAM codes.
Analytical Wall Function• Based on the analytical solution of the simplified Reynolds equations and takes
into account such effects as convection and pressure gradients as well as the influence of buoyant forces and changes in the thickness of the viscous sublayer.
• Has proved to be successful in many flow problems e.g. Buoyant flows.• Currently available in STREAM and TEAM codes.
Numerical Wall Function• Based on an efficient one-dimensional numerical integration of the simplified
LRN model equations across near-wall cells.• Currently available in STREAM and TEAM codes.
AWF Results in Ascending Pipe FlowAWF Results in Ascending Pipe Flow
• Running STAR-CD for “Spiral Ribs” and measure the effects of CO2 Particle deposition on the heat transfer.
• Running TEAM/STREAM codes for mixed convection and ribbed surfaces and evaluate the effectiveness and performance of AWF.
• Modify the AWF if needed to take into account different flow problems such as ribbed surfaces.
• Development of Code_Saturne by implementing AWF and validation against TEAM/STREAM Codes.
Future WorksFuture Works
THE ENDTHE ENDTHANK YOUTHANK YOU
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