ML21098A129
| ML21098A129 | |
| Person / Time | |
|---|---|
| Issue date: | 04/06/2021 |
| From: | Fierro A, Hopkins M, Lafleur C, Gabe Taylor Office of Nuclear Regulatory Research, Sandia, Univ of New Mexico |
| To: | |
| Kenneth Hamburger | |
| Shared Package | |
| ML21098A124 | List: |
| References | |
| Download: ML21098A129 (16) | |
Text
HEAF Modeling with Sierra M . H o p k i n s 1 , A . F i e r r o 2 , C. L a F l e u r 1 , A . G l ove r 1 , G. Tay l o r 3 Sandia National Laboratories is a multimission laboratory 1 Sandia National Laboratories managed and operated by National Technology &
Engineering Solutions of Sandia, LLC, a wholly owned 2 U n ive r s i t y o f N e w M e x i c o subsidiary of Honeywell International Inc., for the U.S.
Department of Energys National Nuclear Security 3 N a t i o n a l Re g u l a t o r y C o m m i s s i o n Administration under contract DE-NA0003525. SAND2021-4079 PE
Sierra Plasma Arc Modeling The conduction of current through the gas (arc) is the source of gas heating, melting and vaporization of metal, and radiation.
The NIST simulation software Fire Dynamics Simulator (FDS) has expertise in gas heating and transport mechanisms but does not have a capability for accurate modeling of the arc physics. Arc domain Sandia National Laboratories (SNL) has extensive capability and expertise in simulating arc physics. Scales for arc physics are micron (and smaller) and require accurate modeling of charged particle transport to capture localized heating effects.
The current approach is to use a Sierra model for the arc and local gas transport, then transfer results to FDS for the full domain transport problem. (walls removed for viewing cabinet internals) 2
HEAF - a Complex Multi-scale Coupled Physics Problem Arc Physics Electrode Melting/Vaporization Gas Heating Radiation (m scale) (mm scale) (cm-to-m scale) (m scale)
Feedback from different phenomena lead to a coupled physics problem 3
Arc Model Overview Electrode Heating Plasma Arc Model Model Aria Solution The Sierra model couples together hydrodynamics (Fuego), plasma physics (Aria), and radiation transport (Nalu).
It is possible to investigate differences in electrode materials, gas composition, gas optical thickness, Gas Transport and other parameters, depending on resource Model allocation.
Fuego Solution The model currently assumes a DC plasma discharge (providing time-averaged heating rates).
Radiation Transport Model Nalu Solution 4
Example Coupled Problem Entire domain Electrodes (also calorimeters)
Energy Radiation Gas region Mass Momentum Plasma (arc) region Turbulent kinetic energy Potential Energy Current density Radiation (Nalu)
Charged species (provide plasma region (provide gas region temperature) energy source term) 5
Open Box OBMV4 Nominal parameters:
- 6900 V L-L system voltage
- 14.3 kA
- 264 V L-N arc voltage
- 5 s duration Model Setup:
- Injection of 14.3 kA (electron current) from middle electrode.
- Middle and left electrode fixed at -264 V.
- Right electrode and walls held at ground.
6
Temperature Evolution (Al Mass Fraction = 0.3) 5000 t = 5 ms temperature (K) 2000 Location 1 1000 Location 2 500 Location 3 0
0 3 6 9 time (ms)
Have not yet reached a steady-state temperature in the plasma volume.
Heating term from arc has stabilized.
Open Box - OBMV4 7
Temperature Rise Difference in Cu vs. Al 5000 t = 5 ms temperature (K)
Probe location This simulation does not yet 2500 include the Al combustion reaction
-- in the process of testing it.
0 0 3 6 9 time (ms)
Open Box - OBMV4 8
Influence of Al Mass Fraction 5000 t = 5 ms temperature (K)
Increasing Al mass fraction Probe location 2500 (0.01, 0.1, 0.3) 0 0 3 6 9 time (ms)
Open Box - OBMV4 9
Medium Voltage Switchgear Simulations - 2018 KEMA Test Focus on plasma region only Nominal parameters:
- 6900 V L-L system voltage
- 25.76 kA
- 246 V L-N arc voltage
- 2 s duration No metal or combustion reaction included Model setup:
- Injection of 25.76 kA (electron current) from middle electrode to right electrode.
- Middle and left electrode fixed at -246 V.
- Other electrode and surfaces at ground.
10
Localized Heating Locations of gas heating due to arc (plasma) formation.
90% total 50% total 10% total power NRC 2018 KEMA Test 11
Evolution of gas temperature and heating source NRC 2018 KEMA Test 12
Current Activity Complete Al Oxidation Reaction
- Al + O2 AlO + O Continue definition of hand-off parameters for plasma arc source term to FDS model
- Power
- Radiation fraction
- Compare temperatures between FDS and Sierra Develop other geometries and operating conditions for ZOI calculations 13
Backup Slides Follow 14
Fully-coupled Model Equations Gas dynamics Plasma arc (drift-diffusion approximation)
(charged species
+ + = (continuity) + =
continuity)
+ = 0 (momentum) = +/- ( ) (flux term)
( ) 2
( ) (electrostatic voltage
+ T = + (energy) = =
and electric field) 1-term turbulence model equation
=
Species transport (Al/Cu)
(Heating/Coupling between equations)
Radiation transport (transport)
(boundaries)
(energy source) 15
Metal Vapor Fraction
- We showed 30% but we include other fractions
- Literature shows that our guesses are reasonable
- There are no measurements of droplet vs. vapor distribution of electrode material 16