gerard schepers - advanced aerodynamic tools for large rotors (avatar) project
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www.eera-avatar.eu
This project has received funding from the European Union’s Seventh Programme for research, technological development and demonstration under grand agreement No FP7-ENERGY-2013-1/n° 608396 .
AVATAR projectAdvanced Aerodynamic Tools for lArge Rotors
Gerard Schepers
2016 Wind Turbine Blade WorkshopSandia National Laboratories, USA
August 31st, 2016
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List of Contents
q Introductionintotheprojectq DesignofAVATARReferenceWindTurbine1)q Aerodynamics athighReynoldsnumbers
• Airfoil measurements inpressurized DNW-HDGtunnel2)q Aero-elasticity oflargeturbinesatyaw
• BEMversusfreevortexwakeaerodynamic modelling3)
19-09-16
1) Acknowledgement G.Sieros,M.Stettner2) Acknowledgement O.Ceyhan,O.Pires3) AcknowledgementK.Boorsma,S.Voutsinas
Andallotherprojectpartners!
FP7-ENERGY-2013-1/ n° 608396 3
EU FP7 Project initiated by EERA
1. Energy Research Centre of the Netherlands, ECN (Coordinator)
2. Delft University of Technology, TUDelft
3. Technical University of Denmark, DTU
4. Fraunhofer IWES
5. University of Oldenburg, Forwind
6. University of Stuttgart, USTUTT
7. National Renewable Energy Centre, CENER
8. University of Liverpool/University of Glasgow, ULIV/UoG
9. Centre for Renewable Energy Sources and Saving, CRES
10.National Technical University of Greece, NTUA
11.Politecnico di Milano, Polimi
12.GE Global Research, Zweigniederlassung der General Electric Deutschland Holding GmbH, GE
13.LM Wind Power, LM
19-09-16
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Period
• Project period: November 1st 2013- November 1st 2017
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Main motivation for AVATAR:Aerodynamics of large wind turbines (10-20MW)
• We simply don’t know if present aerodynamic models are good enough to design 10MW+ turbines• 10MW+ rotors violate assumptions in current aerodynamic tools,
e.g.:– Reynoldsnumbereffects,– Compressibility effects– Thick(er)airfoils– Flowtransitionandseparation,– (More)flexibleblades– Flowdevices• Hence 10MW+ designs fall outside the validated range of
current state of the art tools.
19-09-16
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Avatar: Main objective
To bring the aerodynamic and fluid-structure models to a
next level and calibrate them for all relevant aspects of
large (10MW+) wind turbines
19-09-16
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Avatar: Work procedure– Problem:No10MWturbinesareonthemarketyetforvalidation– Hence:Validatesubmodels againstexperiments
• PressurizedHDGtunnelofGermanDutchWindTunnelfacilities(DNW)• AirfoilmeasurementsatReynoldsnumbersuptoRE=15M andlowMach(<0.2)
• LM:Windtunnelairfoilmeasurements• Forwind:Windtunnelairfoilmeasurementsatrepresentativeturbulence• TUDelft:Windtunnelexperimentsonairfoilswithvortexgenerators,flaps• NTUA:Windtunnelexperiments onairfoils with/withoutvortex generators• DTU:Danaero:Aerodynamicfieldexperimentsona2.3MWturbineandsupporting2Dwindtunnelmeasurements
19-09-16
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Avatar: Work procedure
Usethedifferentmodelsfrompartnersintheprojecto Itisacooperation project!o Intheprojectwehavemanymodelswhichrangefromcomputational
efficient‘engineering’toolstohighfidelitybutcomputationallyexpensivetools
o Engineeringtoolsareneeded inindustrial designcodes1)o Highfidelitymodels(andintermediatemodels)feedinformationtowards
engineeringmodels
19-09-16
1)J.G.Schepers‘Engineeringmodelsinwindenergyaerodynamics,’(2012).http://repository.tudelft.nl/islandora/object/uuid:92123c07-cc12-4945-973f-103bd744ec87/?collection=research
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Avatar: Work procedure
• Demonstratethevalueoftheimprovedtoolson10MWreference rotors withandwithoutflowcontroldevices1. INNWIND.EUreferencerotor(moreorlessconventional
designphilosophy)2. AVATARreferencerotorwhichshouldbemore
challengingfromanaerodynamicpointofview(e.g.lowerinduction,longer,moreslenderblades,thickerairfoils,highertipspeed).
• Compareresultsfrom‘old’andimprovedmodelsattheendoftheproject
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List of Contents
q Introductionintotheprojectq DesignofAVATARReferenceWindTurbine1)q Aerodynamics athighReynoldsnumbers
• Airfoil measurements inpressurized DNW-HDGtunnelq Aero-elasticity oflargeturbinesatyaw
• BEMversusfreevortexwakeaerodynamic modelling
19-09-161) Acknowledgement G.Sieros,M.Stettner
AVATAR RWT
Power: 10MW 10MW
Rotordiameter: 178.3m 205.8m
WTPD: 400W/m2 300W/m2
Axialinduction: 0.3 0.24
RPMàTip speed 9.8rpmà 90m/s 9.8à103.4m/s
Hubheight: 119m 132.7m
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Classical Approach versus Low Induction
• PowerCoefficient flataroundBetzmaximum(a=1/3)
• Aerodynamic loadcoefficientstronglydependantona
• Increasediameterà maintainaerodynamicloadsà increasepower
2
3)1(4
21 aaAU
PCP ==
0
0.2
0.4
0.6
0.8
1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6
Cdax
Cp
)1(4
21
.2
. aaAU
axDC axD ==
a[-]
FP7-ENERGY-2013-1/ n° 608396 13
Design of AVATAR RWT
• 5% Increase in energy production due to larger diameter• Key rotor load levels are maintained• Non-rotor loads exceededà Redesign of AVATAR rotor at end of project• Note: LCOE of AVATAR turbine assessed
in 1) taking into account additionaladvantage of lower wake effects
1)R.Quinn, B.Bulder,J.G.SchepersAparametricinvestigation intotheeffectoflowinductionrotor(LIR)windturbinesontheLCoE ofa1GWoffshorewindfarminaNorthSeawindclimate,EERA-Deepwind 2016
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Design of AVATAR RWT
• The operational conditions
Section Thickness Re (rated) Ma (rated) Re (Min) Ma (Min)60.0% 7.0×106 0.05 4.4×106 0.03
40.1% 11.0×106 0.07 7.0×106 0.05
35.0% 14.0×106 0.09 9.0×106 0.06
30.0% 17.0×106 0.12 10.0×106 0.07
24.0% 20.0×106 0.16 12.0×106 0.10
24.0% 16.0×106 0.25 11.0×106 0.15
24.0% 13.0×106 0.30 8.0×106 0.18
21.0% 20.0×106 0.16 12.0×106 0.10
21.0% 16.0×106 0.25 11.0×106 0.15
21.0% 13.0×106 0.30 8.0×106 0.18
Section Thickness Re (rated) Ma (rated) Re (Min) Ma (Min)60.0% 7.0×106 0.05 4.4×106 0.03
40.1% 11.0×106 0.07 7.0×106 0.05
35.0% 14.0×106 0.09 9.0×106 0.06
30.0% 17.0×106 0.12 10.0×106 0.07
24.0% 20.0×106 0.16 12.0×106 0.10
24.0% 16.0×106 0.25 11.0×106 0.15
24.0% 13.0×106 0.30 8.0×106 0.18
21.0% 20.0×106 0.16 12.0×106 0.10
21.0% 16.0×106 0.25 11.0×106 0.15
21.0% 13.0×106 0.30 8.0×106 0.18
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List of Contents
q Introductionintotheprojectq DesignofAVATARReferenceWindTurbineq Aerodynamics athighReynolds numbers
• Airfoil measurements inpressurized DNW-HDGtunnel1)q Aero-elasticity oflargeturbinesatyaw
• BEMversusfreevortexwakeaerodynamic modelling
19-09-16
1) Acknowledgement O.Ceyhan,O.Pires
FP7-ENERGY-2013-1/ n° 608396
Measurements in DNW-HDG pressurized tunnel
• Measurements up to Re = 15M (and low M)• DU00-W-212 selected as common airfoil– Alsomeasuredby:– LMuptoRE=6M– Forwind atcontrolledturbulentconditionsuptoRe=1M
• Results are brought into a ‘blind test’ – Measurementscomparedwithcalculations– Blindtestincludedparticipantsoutsideproject
DNW-HDGmodel,c=15cm
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DNW-HDG Wind Tunnel
General Tunnel Characteristics
Test section : 60cmx60cmFan Rpm : 200 – 820 Fan blade angle
fixedTunnel Pres. : 1 – 100×105 PaTunnel Temp.: ambient to 45°C
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Test Section
Probeholderforhotwire
90PTsathalfspan
Wakerake118pitottubes6pressuretaps
Kulites4pressureside1suctionside
3-componentBalance
Sensicam &UVLED’sFlowvisualization
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Participants/Codes
Test1.Re=3mil
Test2.Re=6mil-1
Test3.Re=6mil-2
Test4.Re=9mil-1
Test5.Re=9mil-2
Test6. Test7.Re=12mil Re=15mil
Pt [bars] 12 34 67 34 67 67 60Vtunnel [m/s] 25.6 19 10 28.6 15 20 28.4
FullCFD
DTU/EllipSys FullyturbulentTransition Yes Yes Yes Yes Yes Yes Yes
KIEL/TAU FullyturbulentTransition Yes Yes Yes Yes Yes Yes Yes
NTUA/Mapflow FullyturbulentTransition Yes Yes Yes Yes Yes Yes Yes
UoG/HMB Fullyturbulent Yes YesTransition Yes Yes
Forwind-IWES/OpenFOAM Fullyturbulent Yes Yes Yes Yes Yes Yes YesTransition
Pane
lMetho
ds USTUTT/XFOILvUSTUTTFullyturbulent
Transition Yes Yes Yes Yes Yes Yes Yes
ORECatapult/XFOILv6.96Fullyturbulent
Transition Yes Yes Yes Yes Yes Yes Yes
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DNW-HDG Full CFD calculations vs measurementsEffect in Blade Design parameter: Cl/Cd
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpDTU-EllipsysNTUA-MaPFlowKiel-TAUF-I-OpenFOAMUoG-HMB
Test1 Rey=3đ106
Ti3 ( 0.09% )
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
AlphaC
l/Cd
ExpDTU-EllipsysNTUA-MaPFlowKiel-TAU-F-I-OpenFOAMUoG-HMB
Test3 Rey=6đ106
Ti3 ( 0.2% )
FP7-ENERGY-2013-1/ n° 608396
DNW-HDG Full CFD calculations vs measurementsEffect in Blade Design parameter: Cl/Cd
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpDTU-EllipsysNTUA-MaPFlowKiel-TAUF-I-OpenFOAM
Test5 Rey=9đ106
Ti3 ( 0.24% )
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpDTU-EllipsysNTUA-MaPFlowKiel-TAUF-I-OpenFOAM
Test7 Rey=15đ106
Ti3 ( 0.33% )
FP7-ENERGY-2013-1/ n° 608396
DNW-HDG Panel code calculations vs measurementsEffect in Blade Design parameter: Cl/Cd
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpORE-XFOILUoS-XFOIL*DTU-EllipSys
Test1 Rey=3đ106
Ti3 ( 0.09% )
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpORE-XFOILUoS-XFOIL*DTU-EllipSys
Test3 Rey=6đ106
Ti3 ( 0.2% )
FP7-ENERGY-2013-1/ n° 608396
DNW-HDG Panel code calculations vs measurementsEffect in Blade Design parameter: Cl/Cd
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpORE-XFOILUoS-XFOIL*DTU-EllipSys
Test5 Rey=9đ106
Ti3 ( 0.24% )
-5 0 5 10 150
20
40
60
80
100
120
140
160
180
Alpha
Cl/C
d
ExpORE-XFOILUoS-XFOIL*DTU-EllipSys
Test7 Rey=15đ106
Ti3 ( 0.33% )
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Blind test, main conclusion
– cl/cd largely determines theoptimal aerodynamicdesign– importance ofboundary layer transition oncl/cdhasbeenconfirmed:– eN method performswellatall Reynoldsnumbers– Correlationbased transitionmethod (stateofthe artinmany CFDtools!)deficient athighReynoldsnumbers 1)
– Newversion ofcorrelation based transitionmodelisdevelopedwithbetter performance2)
1) Niels N. Sørensen et al Prediction of airfoil performance at high Reynolds numbers EFMC 2014, Copenhagen 17-20 Sept 2014 2) S. Colonia et al Calibration of the g equation transition model for High Reynolds flows at low Mach To be published at the Science
of Matking Torque, October 2016
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List of Contents
q Introductionintotheprojectq DesignofAVATARReferenceWindTurbineq Aerodynamics athighReynoldsnumbers
• Airfoil measurements inpressurized DNW-HDGtunnelq Aero-elasticity oflargeturbinesatyaw
• BEMversusfreevortexwakeaerodynamic modelling1)
19-09-161) AcknowledgementK.Boorsma,S.Voutsinas
ECN Aero-module
26June17,2010
• ECNAeroModule:Onecodewithaero-modelsofdifferentdegreesoffidelity coupledtosamestructuralsolver(PHATAS/FOCUS)• BEM andAWSM (Freeandprescribedvortexwakemodel)• Straightforwardcomparisonofdifferentaerodynamicmodelswithsameinput• Resultsareshownofazimuthalvariationofinducedvelocityatyawed conditions:• AWSM:Physical modelling ofazimuthalvariation ofinduced velocity atyaw• 2BEMimplementations: Conventional Glauert model1)and ECNdeveloped rootvortexmodel2)and 3)
1) H.Glauert, AgeneraltheoryforAutogyroARC-R-M,1111, 1926
2) J.G.SchepersAnengineeringmodelforyawedconditions,developedonbasisofwindtunnelmeasurements,AIAA-99-003937thAerospaceSciencesMeetingandExhibit, AerospaceSciencesMeetings,1999
3) J.G.Schepers‘Engineeringmodelsinwindenergyaerodynamics,’TUDelft PhDthesisISBN:9789461915078, 2012
INNWIND.EU turbineResults at 30 degrees yaw (30% and 95% span)
27
§ Induced velocity variation at30%span:• 90degrees azimuth:
• Rootvortexeffects clearly apparentinvortexwakemethods (AWSM and AWSM-Prescribed)• Conventional Glauertmodelfor induced velocity variation deficient• Rootvortexeffects predicted wellby ECN-rv
§ Induced velocity variation at30%span:Effectofrootvortexatouter blade partinECN-rv will be reduced
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Summary
• AVATAR is an EU FP7 projects which aims to validate, improve and calibrateaerodynamic models for 10MW+ turbines with and without flow devices and withand without aero-elastic effects
• Several (wind tunnel) measurements have been taken which have helped to validateand improve (sub) models relevant for 10MW+ turbines
• Models of different degrees of fidelity are evaluated on two 10 MW reference wind turbines:– AVATARlowinduction turbinewith specialaerodynamic challenges– INNWIND.EUconventional induction turbine
FP7-ENERGY-2013-1/ n° 608396 29
Summary
• The amount of results from the AVATAR project is far too much to present in 15-20 minutes• AVATAR led to several model improvements and lessons learned e.g:
– Transition modelling• Originalcorrelation based transitionmodels deficient athighReynoldsnumbers• Updated version ofcorrelation based transition models hasbecome available• Guidelineson theemploymentoftransition(andturbulence)modelsformulated
– Improved predictions for lowMachconditions incompressible codes– Improved models for thick airfoils– Improved modelsfor flowdevices (flaps, vortexgenerators,rootspoilers)– Firstpossibilities for rotormodelimprovements identified (many morewill follow…)– Improved calculational efficiency and reduced timeto set-upcalculation– Expansion/integration ofcodes(e.g.coupling ofaero-elastic models to freevortexwakemethods)– Bestpracticeguidelines ongridresolutions andtemporalresolution
• Needforvortexcorrectionsatsomegridtopologieswithlimiteddomainsize– CalibrationofengineeringmethodsfromCFDnotstraightforward
• TechniquesaredevelopedandtestedtoderiveliftinglinevariablesfromCFD– Manymoreimprovementsandlessons learnedwillfollow!
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Dissemination of results
– All technical deliverablesarepublic:http://www.eera-avatar.eu/publications-results-and-links/
– Webbased validation platformisunder development(http://windbench.net/avatar)
– AVATARsessionatIRPWIND-EERAJointWindR&Dconference,September19,Amsterdam,theNetherlands– Introduction (GerardSchepers,ECN)– AdvancedAerodynamicModelling(NielsSørensen,DTU)– Flowdeviceaerodynamics(AlvaroGonzalez,CENER)– Roadmapforfurtherengineeringmodellingimprovements(GerardSchepers,ECN)
– AVATARsessionatScience ofMakingTorque,October 7,MunichGermany– 5Oralpresentations
– LatestresultsfromtheEUprojectAVATAR:Aerodynamicmodellingof10MWwindturbines(GerardSchepers(ECN) etal)– CFDcodecomparison for2Dairfoilflows (NielsSørensen (DTU)etal)– Experimentalbenchmarkandcodevalidationforairfoilsequippedwithpassivevortexgenerators (DanielBaldacchino (TUDelft)etal)– ComputingtheflowpastVortexGenerators:Comparison betweenRANSSimulationsandExperiments(M.Manolesos(NTUA) etal)– ResultsoftheAVATARprojectforthevalidationof2DaerodynamicmodelswithexperimentaldataoftheDU95W180airfoilwithunsteadyflap(CarlosFereira (TUDelft) etal)
– Introduction to 7posters
Consortium
FP7-ENERGY-2013-1/ n° 608396
Coordinator:
Partners in alphabetical order:
This project has received funding from the European Union’s Seventh Programme for research, technological development and demonstration under grand agreement No FP7-ENERGY-2013-1/n° 608396 .
Thank you for your attention