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Meteorologically Driven Wind Turbine SimulationEvan Greer, Mentor: Dr. Marcelo Kobayashi, HARP REU ProgramAugust 2, 2012Contact: [email protected]
globalwindgroup.com
Overview
Introduction and Motivations Creating the geometry Stationary study of turbine geometry Rotating study of turbine geometry Future Plans Acknowledgements
Introduction
Energy Security
High reliability of fossil fuels leads to wide spread use
Set amount of fossil fuel outputs a set amount of energy
Motivations
Introduction of reliability to renewable resources, wind energy in particular
Wind energy is subject to low reliability due to changing weather conditions
Scale predictions of large scale weather patterns to make predictions about the environment around the turbine
The effects of local topography on efficiency will be studied
WRF (weather research and forecasting) model coupled with CFD models
This is the future goal of this research but first a working model of the turbine must be created and studied
Initial studies
Used a sample geometry from Comsol Multiphysics
Played with initial conditions and mesh sizes
Learned how to use the Comsol Multiphysics software Studied introductory tutorial
building a busbar geometry Learned how to set up fluid
flow and thermoelectric physics
Setting up the geometry
• Approximated the geometry of a typical wind turbine
• Height of the tower set at 300 ft
•Length of the rotors set at 200 ft
•Length of the nacelle set at 40 ft
Front View Side View
Blade Domain
• Created for the implementation of the sliding mesh
• Cylindrical region with a height of 80 ft encompassing the blades
• Domain to move with the blades
Flow Domain
• Region where boundary and initial conditions are to be defined
• Created a cylindrical region behind the sliding region to study wake
• Material for the flow set as air and material for turbine set as aluminum
Setting up the mesh
• Generated mesh using tetrahedral elements
•Mesh had to be refined around blades
•Mesh consisted of 93349 elements
Stationary study
Ran a stationary turbulent flow study using a k-ε model
This model has the purpose of understanding how fluid flow is affected by geometry
Setting up physics
Used a simple turbulent flow physical model
Stationary study step with no time dependence
Inlet velocity of 3.219 m/s, this is the average annual wind speed of Honolulu reported by NOAA [1]
Outlet condition was also set to atmospheric pressure
Also, a volume force was introduced on the flow domain
Results
The Rotating Model
Used Rotating Machinery, Turbulent Flow physical model
Moving domains are coupled with stationary domains by identity pairs
At these identity pairs, a flux continuity boundary condition is applied
Navier-Stokes equations are formulated based on rotating and stationary coordinate systems
Issues
Convergence of time stepped solution
Solution would get stuck on calculation of time step
Many issues with script files and runs on supercomputer
Supercomputing issues
Issues with licensing Jobs would terminate because of lack of
licensing on multiple nodes Solved with batch and cluster computing add-on
to job configurations within Comsol Issues with node communication
Comsol would get kicked nodes Solved using MPD (Multi processing Daemon)
used by Comsol to communicate between nodes Accomplished through modification of script files
with the help of Andrew Yukitomo
Simplification
Isolated rotating geometry
Try to get rotating blade working without pairing
Added input and output condition
Modifications
Added pairing and flow continuity condition between stationary and rotating domains
Used overlapping domains and input and output conditions
Results
Further modifications
Used non-overlapping domains
Got rid of input and output conditions, instead used a pressure point constraint
Increased number of iterations used by the solver
The Next Steps
Complete the set up of the full rotating geometry
Get the blade study to run for larger time scales Further work needs to be done to understand where
and why the convergence errors are occurring Understanding how to make a more accurate mesh
Introduce the stationary wake region and a two dimensional pairing region
Introduce the flow domain and three dimensional pairing and get the complete model to run
Get the rotation of the turbine to be dictated by inlet velocity conditions This will involve delving deeper into the
interface to understand how to program physical models
Future Plans
Project benchmarks: Creating geometry Modeling stationary case Implementation of sliding mesh Implementation of Large Eddy
Simulation Implementation of WRF data
This research will be continued under a NASA space grant in the fall
Acknowledgements
I would like to thank Dr. Susan Brown for giving me the opportunity to be a part of this program and Dr. Marcelo Kobayashi for his continued support and allowing me to share in his research. I also want to acknowledge Andrew Yukitomo for his continued help with script files and supercomputing issues and HOSC for allowing us to use the supercomputing facilities for our work.
"This material is based upon work supported by the National Science Foundation under Grant No. 0852082. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."
References
[1] Delliger, Dan, 2008, Average Wind Speed, Comparative Climate Data, http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/avgwind.html (July 5, 2012)
[2] Laminar Flow in a Baffled Stirred Mixer. Comsol Multiphysics 4.3 sample program documentation, 2012