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

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

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%

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

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

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 jema@lmwindpower.com E info@lmwindpower.com

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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