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ByBy
ADVANCES IN AERODYNAMICS
OF WIND TURBINE BLADES
Herning / October 3 / 2017Jesper Madsen
Chief Engineer, Aerodynamics & Acoustics
WIND ENERGY DENMARK – Annual Event 2017
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1. Aerodynamic design and developments
2. Innovative tip designs
3. LM Vortex Generator Mk II
Agenda
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Aerodynamic blade design considerations
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Focus areas:
Low-Noise performanceBlade design
Devices
Aerodynamic tailoring:Wide variation in LM-Airfoil characteristics covers requirements from small on-shore turbines to ultra-long off-shore blades
Blade optimization
Leading Edge Erosion:Aerodynamic impact of eroded blade
Erosion protection systems
DevicesSerrations (acoustics)
Vortex Generators
T-spoiler (root performance)
Aerodynamic DevelopmentsLM Serrations
LM T-Spoiler
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Objectives:
Reduction of Turbine Wake to improve total windfarm yield
Optimize blade tip aerodynamics
Reduction of Noise
Innovative Tip Designs
Conventional Blade Tip
Winglet
Turbulators
ECN Patented
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Results:
Increase in power output between 5% to 6% at wind speeds between 6 m/s and 9 m/s for conventional blade tip extension.
Extending blade accounts for about 4% power increase – remainder is optimization in shape.
Tip ExtensionField Installation and Testing
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LM Vortex Generator Mk IIContinuous Improvement
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Vortex generators improve blade performance by reducing flow separation
VGs maintain attached
flow
Clean surface –
flow is separating
Low AoA
Max. lift AoA
Stall AoA
Without VGs With VGs
Smooth airflow Vortex airflow
Boundary layer
separated
Boundary layer
attached
Uncontrolled
turbulence
Controlled
vortices
Compared to a clean blade, VG’s typically improves AEP by 0.5% – 1%
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Mk II consists of a single vane on base plate
Vanes are mounted on top of blade surface using a
tape interface
VG’s are available in different sizes, so range of
applications can be covered
Bonding process is covered by international
published patent application
Material changed to a tougher, more UV stable
plastic
LM Vortex Generators Mk II
OLD
NEW
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Panel-VG flush-mounted in groove
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VG design philosophy completely re-engineered
Reliable performance predictions for wide range of airfoil thicknesses, VG
configurations, combinations with other Add-Ons obtained from LM Wind tunnel tests
Optimal and Robust VG design (geometry and configuration) understanding obtained
from exhaustive wind tunnel testing
LM Vortex Generator’s Mk II – Single Fin
Some Tested
Geometries
MKII VG’s – Close up View
MKII VG’s On an Airfoil in LM Wind Tunnel Performance coefficients from wind tunnel test
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LM wind tunnel
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Experimental results from LM Wind Power Low Speed Wind Tunnel (LM LSWT) measurements
Objective: reduction in drag along with increased or same lift and delayed stall
Parameters:
Foot plate shape and thickness
Chord wise placement
Fin geometry
Triangular
Height (h)
Length (l)
Configuration:
Spacing between pairs (z)
Spacing between fins (s)
Fin angle (β)
Some results are presented in next slides
Experimental Optimization of VG Parameters
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VGs closer to the leading edge of the profile has highest
increment in the Cl
But the same time the increment in the Cd is also more
Effect of chord wise location
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VG with lower height performing better in terms of Clmax and
AoA-Clmax and also drag
h/c=2% is too high
Effect of VG height
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z/h=3 has highest increment in Cl (with more Cd)
z/h=5 has high Cl/Cd ratio over wider AOA range
z/h=7 has highest maximum Cl/Cd (also better than clean)
Effect of VG spacing
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Automated Design ToolsVG positioning on blade surface
Several checks are
built in:
Aerodynamic
force
Centrifugal
force
Blade surface
curvature
VG angle
Etc.
Different sizes
Mould Marks
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Continuous Improvement project to improve the existing LM VG offering along with
Improved Aerodynamics
Improved Reliability
Simplified and Robust installation process
Enables service / retro-fit offerings
Completely re-designed approach having single fins in an integrated mounting system with focusing on each of the above aspects
Exhaustively Tested and Validated designs for performance
LM Vortex Generator’s Mk II
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Thank you for your time
Contact details: Head quarters:
Jesper Madsen LM Wind Power
Chief Engineer Jupitervej 6
Aerodynamics & Acoustics 6000 Kolding
Denmark
Tel +45 79 84 07 64 Tel +45 79 84 00 00
Mob +45 51 38 87 64 Fax +45 79 84 00 01
E [email protected] E [email protected]
W lmwindpower.com
Note:
The contents of this presentation are confidential and may not be copied,
distributed, published or reproduced in whole or in part, or disclosed or
distributed by recipients to any other person.
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