3D Conjugate Heat Transfer Analysis of the Next Generation Inner Reflector Plug for the Spallation Neutron Source

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1 3D Conjugate Heat Transfer Analysis of the Next Generation Inner Reflector Plug for the Spallation Neutron Source Ashraf Abdou Oak Ridge National Laboratory, Oak Ridge TN, USA March 18-20, 2013 STAR Global Conference 2013 Orlando, Florida, USA

2 The Spallation Neutron Source at ORNL Central Laboratory & Office Complex LINAC Accelerate the beam to 1 GeV Accumulator Ring Compress 1 msec long pulse to 700 nsec Center for Nanophase Material Science Target building & neutron instruments Proton beam pulses to Target at 60 Hz 2 Managed by UT-Battelle

3 SNS Instruments Cover a Wide Range of Science 18 neutron beam lines some accommodate more that 1 instrument 3 Managed by UT-Battelle

4 SNS Target Systems Core Region Proton Beam Liquid Mercury Target Module Reflector Plugs 4 Managed by UT-Battelle

5 SNS Target Systems Core Region Moderators (4) Inner Reflector Plug Outer Reflector Plug Core Vessel Proton Beam Window Target Neutron Beam Lines Proton Beam 5 Managed by UT-Battelle

6 CFD Simulations of SNS Systems SNS Systems are built in PRO-E Creo parametrics Neutronics Analysis Codes: MCNPX and other codes Volumetric power deposition in Liquids and solids Thermal-Hydraulic Analysis Codes: STAR-CCM+V7, ANSYS-CFX, Fluent V14.5 and ICEM-CFD Grids: conformal Hexahedral and Polyhedral Conjugate Heat Transfer Analysis Two-Phase Flow for Gas layers and gas bubbles Fluids: Liquid mercury, heavy and light water, supercritical hydrogen and gases Stress Analysis Codes: ABAQUS and ANSYS 6 Managed by UT-Battelle

7 2 nd Generation Inner Reflector Plug (IRP) Intermediate IRP Stainless Steel OD X 22 tall, 4095 lbs. Middle Reflector Plug (MRP) Be Proton Beam Target Lower IRP SS, Be, Al, and Cd OD X 73 tall, 7000 lbs. Be 7 Managed by UT-Battelle Existing IRP

8 Inlet side Outlet side 2 nd Generation MRP Design 2 SS inserts Outlet Inlet 80 gpm 40 C 0.25 inch Heavy Water 0.25 inch Proton Beam Hole diameters in the inlet side is 0.5 inch Hole diameters in the outlet side is inch Water Plenum 8 Managed by UT-Battelle Aluminum Can

9 2 nd Generation IRP Design Light Water Pre-Moderators 15 gpm each 40 C 40 gpm 40 C Outlet gpm 40 C 40 gpm 40 C Beryllium Aluminum 9 Managed by UT-Battelle for the U.S. Department of Energy STAR Global gpm Conference C Heavy Water

10 Volumetric Heat Generation (W/m 3 ) in Aluminum at 2 MW Beam Power IRP MRP 10 Managed by UT-Battelle

11 Temperature Contours at Water/SS, Water/AL and Water tubes/ss interfaces SS/Water tubes interface Water/AL interface SS Insert1 SS Insert2 11 Managed by UT-Battelle Water/SS interface

12 SNS Mercury Target Module Mercury vessel surrounded by a water-cooled shroud Mercury Target Vessel Water-cooled Shroud Proton Beam 12 L/s quasi-stagnation region at the center of the window Re = Bulk mercury flow 12 Managed by UT-Battelle

13 Conjugate Heat Transfer of SNS Liquid Mercury (1.54 MW Beam Power) Constant Volume Heating Process Leads to Large Pressure Pulse in Liquid Mercury Deposited Power In SS: 63.8 kw 13 Managed by UT-Battelle Deposited Power in HG: kw

14 Conjugate Heat Transfer of SNS Liquid Mercury K- SST Mentor turbulence model Turbulent Prantdl number 14 Managed by UT-Battelle

15 Cavitation Damage Erosion of the Target Module Target # 8 is running at about 1 MW Beam Power Specimen diameter: 60 mm Original thickness: 3 mm 15 Managed by UT-Battelle Off-center, bulk Hg surface Center, bulk Hg surface

16 Textured SNS window: 24 L/s Close up view Horizontal V Grooves Horizontal V Grooves Vertical V Grooves Conical pits Stagnation Zone Vertical V Grooves Sweeping Mercury Flow Sweeping Mercury Flow Horizontal V Grooves Horizontal V Grooves Horizontal V Grooves Horizontal V Grooves 16 Managed by UT-Battelle Gas Injection: 500 sccm per port

17 Experiments in liquid Mercury: Video of Textured Gas Wall at the window (24L/s) Vertical Grooves Conical Pits Vertical Grooves Horizontal Feeder Grooves He gas injection at 500 sccm each 17 Managed by UT-Battelle

18 Time Averaged Helium VF Contours 18 Managed by UT-Battelle

19 Animation of Gas Volume Fraction contours (24 L/s) 19 Managed by UT-Battelle

20 Summary STAR-CCM+ is being used at SNS for : conjugate heat transfer with water in complex geometries conjugate heat transfer with liquid metal in separated flows Two-Phase flow for developing gas wall layer over textured wall The simulations provide guidance for the experiments, and may be used as a diagnostic tool for probing inside the opaque mercury. CFD is thus demonstrated to be a promising method for optimization of a gas wall to mitigate cavitation erosion of the SNS target. Comments: Communication between PRO-E Creo and STAR-CCM+ CAD thru 3D CAD Exchange to prepare the models for conformal polyhedral grid Interface Imprinter in STAR-CCM+ CAD with importing Para solid and IGES files Parametric studies: Writing the solution settings, BCs and etc. into a file then read this file for different cases for easy setup for the models Comparison between mapped interfaces with direct and indirect mapping for both conformal and non- conformal grids 20 Managed by UT-Battelle

21 Thanks for your attention 21 Managed by UT-Battelle