Maximizing efficiency of wind turbines is a vital consideration for operators, and managing erosion is a vital method to achieve this. Studies have consistently shown that erosion can lead to a loss in annual energy production (AEP) of up to 20% on severe cases. This figure is hard to ignore, and highlights the ROI benefits that can be achieved from paying close attention to erosion. The heart of the issue is the fact that wind blades come into contact with various elements in the air at rotation speeds up to 250 mph, leading to erosion in the form of pitting, gouging and delamination of the edge of the blade. This erosion not only compromises the integrity of the blade, but also impacts its aerodynamic efficiency, causing a significant loss in AEP. This loss can be compounded by the downtime necessary to make repairs to turbines, so owners have important motivations for protecting blades against erosion and making repairs quickly. In severe cases of erosion can even lead up to blade replacement which can get very expensive. 3M™ Wind Energy has extensive experience managing erosion, understanding the causes and effects of leading edge erosion, and bringing education to the industry on this problem. We have had decades of experience in understanding erosions and how to effectively prevent this.

1. #WindWebinar

2. #WindWebinar
q This webinar will be available afterwards at
www.windpowerengineering.com & email
q Q&A at the end of the presentation
q Hashtag for this webinar: #WindWebinar
Before We Start

3. #WindWebinar
Introducing the Featured Speakers
MODERATOR FEATURED SPEAKER
Santhosh Chandrabalan
Global Business Manager
3M Wind Energy
Paul Dvorak
Editorial Director
Windpower Engineering

4. #WindWebinar
Latest Protection Methods
Against Leading Edge Erosion
For Increased Tip Speeds
Santhosh K Chandrabalan
Global Business Manager – Wind Energy
3M Renewable Energy Division

5. #WindWebinar

6. 3M Renewable Energy Division
#WindWebinar
6 © 3M 2014. All rights reserved.
§ 3M enables more efficient and more reliable wind turbines, built faster and safer
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3M Renewable Energy Division – Wind Energy

7. 3M Renewable Energy Division
#WindWebinar
7 © 3M 2014. All rights reserved.
Vortex Generators
Aerodynamic Optimization of
Installed Wind Turbines with
customized enhancement solutions
Blade Bonding Adhesive
Offering long pot life and s<ll 50% faster
cure - addi<onally increasing crack
resistance and fa<gue behavior
Dry Layup Adhesive
Red colored spray adhesive to efficiently fix
the fiber mats during dry layup
Erosion Protec5on Solu5ons
Tapes & Coa<ng offering superior
erosion resistance and process-
advantages in blade produc<on
§ Reduce cycle <me
§ Decrease variability
§ Increase blade throughput
§ Lower process cost
§ Increase strength
§ Decrease weight
§ Enhance mechanical proper<es
§ Improve laminate quality
§ Lower blade cost
§ Improve resistance to erosion
§ Improve aerodynamics
§ Enable aTachments to surface
§ Simplify maintenance
§ Lower O&M cost
Rotorblade
Surface
Rotorblade
Structure
Rotorblade
Process
Acrylic Foam Tapes
For mess-free bonding applications
that require high durability and
bonding strength while being mess-
free and fast to apply
Wind Fillers
Easy and fast to apply filler
offering significant <me
savings before sanding
Sealants & Adhesives
High-performance sealing
and bonding materials for
all areas of the blade
3M`s Wind PorAolio

8. 3M Renewable Energy Division
#WindWebinar
Field Pictures of Leading Edge Erosion
Source: WKA/GES & DRTS

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#WindWebinar
Higher Requirements for Surface Integrity
§ Longer blades with higher <p speeds
§ Offshore installa<ons
§ Installa<ons in other demanding
environments (e.g. deserts and cold climates)
§ Current commercial available products
do not meet erosion resistance requirements
Source: LM Wind Power – IQPC & Sandia

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#WindWebinar
Erosion - Observa<ons from the Field
§ Erosion is a severe problem and can be seen on all blades
§ … irrespec<ve of the turbine loca<on (Onshore, Offshore, Nearshore, Mountains)
§ … irrespec<ve of the hub height (30m – 110m).
§ … irrespec<ve of the paint/coa<ng system used (Gelcoat, Topcoat)
§ … irrespec<ve of the blade length (10m – 45m).
§ … irrespec<ve of the Wind Turbine Generator manufacturer (A Alstom – Z Zond)
§ Erosion is very much depending on
§ … the environmental condi<ons at the turbine loca<on
§ ... the quality of the blade structure and the finishing
§ … the actual <p speed of the turbine
§ A combina<on of high par<cle loaded air
and rain has a significant erosion impact

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#WindWebinar
Effects of Blade Leading Edge
Erosion on Wind Turbine Output

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#WindWebinar
Wind Tunnel Studies at University of Illinois
§ Test Loca<on:
§ University of Illinois
Applied Aerodynamics Group
§ Prof Michael Selig & Agrim Sareen
§ Objec<ve:
§ Determine impact of leading edge erosion on aerodynamics
(lij and drag) at several different
Reynolds numbers (here Re 1,850,000)
on a DU 96-W-180 wind turbine airfoil profile
§ Es<mate power output
(AEP – Annual Energy Produc<on)
for each scenario using PROPID sojware

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#WindWebinar
Erosion Condi<ons Evaluated
§ Created subscale airfoils with leading edge damage using computer generated
random Gaussian distribu<ons
§ 3 of the 9 levels of erosion evaluated are highlighted in this presenta<on
A2 – Moderate Pitting B3 – Pits + Gouges C4 – Pits, Gouges & Delamination
*Model cord length is 18 inches

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#WindWebinar
Leading Edge Status
rDrag
(Measured)
r Lift
(Measured)
rAEP
(Simulated)
rMWh / yr r€ / yr
A2 Erosion
Moderate Pitting
“80% ”11% ”4.2% ”166 ”8,300€
B3 Erosion
Pits & Gouges
“200% ”15% ”9.8% ”386 ”19,300€
C4 Erosion
Pits, Gouges & Delam
“400% ”17% ”20.5% ”808 ”40,400€
Assumptions: 1.5 MW turbine, €50/ MWh, 30% capacity factor
Effect of Leading Edge Erosion on Turbine Output
Onshore – 1.5MW

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#WindWebinar
Benefits of Leading Edge Repair & Protec<on
Source: LM Wind Power – UWIG Wind Turbine Opera<ons and Maintenance Users Group Mee<ng

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#WindWebinar
Products:
3M Wind Blade Protec<on Tape Features & Benefits of a
Proven Solu<on
3M Wind Blade Protec<on Tape Features
§ High durability ensuring long life<me
§ Based on over 40 years of 3M Protec<on Film
experience in aircraj applica<ons and
§ More than 150,000 protected wind turbine rotor blades since 1994
§ Available in various colors (offering superior UV resistance)
3M Wind Blade Protec<on Tape Advantages
§ Significant reduc<on of leading edge erosion
§ Extended maintenance and service intervals
§ Fast & ease of applica<on in OEM and MRO environments
§ Broad applica<on window enabling installa<ons
also under harsh environmental condi<ons (e.g. high humidity levels)

17. 3M Renewable Energy Division
#WindWebinar
Benefits of Leading Edge Repair & Protec<on
Onshore – 1.5MW
Leading Edge Status rAEP
Avg. Materials &
Installation Cost per Blade
Downtime per
Turbine (days)
Years of
Service
ROI (months)
NPV
A2 Erosion
- 4.2% 2,250 € 1 – 2 0.5 – 4
2.7
64,036 €
B3 Erosion
-9.8% 3,250 € 1.5 – 3 1 – 6
1.8
152,788 €
C4 Erosion
-20.5% 4,750 € 5 – 6 1.5 – 7
1.7
320.164 €
Example Calculation Assumption: 1.5 MW turbine, €50/ MWh, 30% capacity factor, NPV: straight line, 5 yr, 15% IRR

18. 3M Renewable Energy Division
#WindWebinar
Conclusion:
Preven<on is more efficient than Repair
Erosion is a severe issue on almost all rotor blades
Erosion can cause significant AEP reduc<ons
§ Pits and gouges reduce AEP from 4% up to 10%
§ Delamina<on reduces AEP up to 20%
Preventa<ve blade repair & protec<on reduces down<me and costs
§ Repair of erosion can cost up to 5.000 Euro Onshore & 44.000 € Offshore
§ 3M Wind Protec<on Tape provide 5 - 10 years of leading edge protec<on
§ ROIs from all scenarios studied were less than 5 months

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#WindWebinar
Tes<ng Methods for
Blade Leading Edge Erosion on
Wind Turbine Output

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#WindWebinar
Advanced Rain Erosion Tests Methods can
simulate what the Blade experiences in Real-Life
Source: LM Wind Power – IQPC

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#WindWebinar
§ Shock waves run though substrate
and water droplet
§ Rayleigh waves run over substrate
§ Wasser jets run over substrate surface
Rain Erosion - Impact Physics
§ “Hard materials” start to break/blister, i.e.
materials start eroding earlier
§ “Elas<c materials” absorb energy

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#WindWebinar
Source: http://www.poly-tech.dk
§ Standard Test Parameters
§ Rota<onal Speed: 125-157 m/s
§ Rain: 25-35 mm/h
§ Droplet Size: 1-2 mm
§ Specimen: Leading edge profile
Helicopter Rain Erosion Tests
Source: UDRI & PolyTech

23. 3M Renewable Energy Division
#WindWebinar
Rain Erosion Tests – PolyTech
Compe<<ve Materials (Special LEP Coa<ngs)
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

24. 3M Renewable Energy Division
#WindWebinar
Rain Erosion Tests – PolyTech
Compe<<ve Materials (Special LEP Coa<ngs)
Test Specifica<ons: V<p [m/s] 140, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

25. 3M Renewable Energy Division
#WindWebinar
Rain Erosion Tests – PolyTech
Compe<<ve Materials (Special LEP Coa<ngs)
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

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#WindWebinar
Rain Erosion Tests – PolyTech
3M Wind Blade Protec<on Tape W8607
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

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#WindWebinar
Rain Erosion Tests – PolyTech
3M Wind Blade Protec<on Coa<ng W4600
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

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#WindWebinar
Rain Erosion Tests ajer UV Exposure – PolyTech
3M Wind Blade Protec<on Coa<ng W4600
§ Erosion Resistance of 3M Wind Blade Protec<on Coa<ng W4600
is not significantly influenced by UV exposure
§
§ UVA-340 lamps match the solar UV spectrum well, especially from 295 to 370 nm
§ UVB-313 lamps include significant unnatural radia<on below the solar cut-off of 295 nm
§ 3M uses and recommends UVA-340 lamps
for accelerated weathering that makes use of UV fluorescent lamps
No influence even ajer 4000h UV

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#WindWebinar
Products:
Introducing the Next Genera<on LEP Protec<on
3M Wind Blade Protec<on Coa<ng W4601
§ W4601 project was ini<ated with the following objec<ves
§ Keep the leading edge performance of W4600 and make it robust
§ Increase the applica<on window for W4600
§ Reduce the curing <me of exis<ng W4600
§ W4600 formula<on was the star<ng point of W4601
§ Product robustness was achieved by adding 3M Proprietary fluoropolymer
§ This addi<ve extends the applica<on window for W4601 up to 85% RH without any loss in
performance
§ The original formula<on was improved to reduce curing <me to 2 hours

30. 3M Renewable Energy Division
#WindWebinar
Introducing the Next Genera<on LEP Protec<on
3M Wind Blade Protec<on Coa<ng W4601
Criteria W4600 W4601
Thixotropy/Sagging 300µm 350µm
Curing Touch dry time ~ 1-1,5h,
Hard dry ~ 8 h,
(cured at 23°C, 50% RH)
Touch dry time ~ 25 min,
Hard dry ~ 1 h,
(cured at 23°C, 50% RH)
Tensile ~900% Elongation at Break
27MPa Tensile Strength
(cured at 23°C, 50% RH)
~700% Elongation at Break
30 Mpa Tensile Strength
(cured at 23°C, 50% RH)
Application Window Loss in Rain Erosion Properties as
humidity increases (similar to
standard coatings)
RET shows no drop in
performance after 18h RET at 85% RH
Applicability Brush and Casting Brush, Spray and Casting
Mixing 1.5:1 3:1 (standard cartridges)
Crysttalization If material is crystallized material
should be recovered by oven
storing for 8h at 40°C
Material shows recovering properties, no
oven storage needed

31. 3M Renewable Energy Division
#WindWebinar
Key Applica<on Factors Influencing Product Performance
Application Factor
Theoritical Impact on
Erosion Resistance
Coating Thickness below recommended level -
Coating Thickness above recommended level +
Humidty during Application & Cure -
Surface Roughness -
Toughness of LEP +
Poor Adhesion between Surface Layers -
Filler O / -
Topcoat O / -
Poor finish Quality (e.g. air entrapment) -
-+ O neutralpositive negative

32. 3M Renewable Energy Division
#WindWebinar
36+ Hour Consistently Proven Performance
§ Profiles Brushed with W4601
§ Recommended applica<on thickness
§ 2X Recommended applica<on thickness
§ 4X Recommended applica<on thickness
§ Profiles with W4601 + PU Filler
§ Recommended applica<on thickness
§ 3X Recommended applica<on thickness
§ Profiles Casted
§ Recommended applica<on thickness
§ 3X Recommended applica<on thickness

33. 3M Renewable Energy Division
#WindWebinar
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm
Rain Erosion Tests of NextGen Coa<ng – PolyTech
3M Wind Blade Protec<on Coa<ng W4601
cured at 23° and 85% r.H.

34. #WindWebinar
Profile brushed, Cured at 23/50, two times (~ 400-500 µm)
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

35. #WindWebinar
Profile brushed, Cured at 23/50, four times (800-1000µm)
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

36. #WindWebinar
1mm PU Filler (W3610) underneath, Profile casted 1 time ,Cured at 23/50; (~350µm)
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

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1mm PU Filler (W3610) underneath, Profile casted 3 times, Cured at 23/50; (~1000µm)
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

38. #WindWebinar
Profile casted one time (~350 µm); Cured at 23/80
Test Specifica<ons: V<p [m/s] 157, Rain [mm/h] 30-35mm, Droplet Size [mm] 1-2mm

39. 3M Renewable Energy Division
#WindWebinar
Key Take-Aways
§ Erosion
§ Erosion is impac<ng the aerodynamic efficiency of a turbine (up to 20%)
§ BeTer Test Standards have to be developed
§ Rain Erosion (Helicopter) Tests are the right intermediate step
§ UVA should be used to age materials
§ 3M is the leading supplier of erosion protec<on solu<ons
§ 3M Wind Blade Protec<on Tape
§ More than 15 years of experience in the wind industry
§ S<ll benchmark in regard to erosion protec<on of rotor blades
§ Current developments to improve ease-of-applica<on and durability
§ 3M Wind Blade Protec<on Coa<ng W4600 and now W4601
§ Liquid VOC-free alterna<ve to our Wind Tape
§ Even beTer performance than 3M Wind Protec<on Tape in erosion tes<ng
§ Quick and easy to apply - with no need for capital investment

40. #WindWebinar
Questions?
Santhosh Chandrabalan
Global Business Manager
3M Wind Energy
schandrabalan@mmm.com
Tel: 651-733-7740
Paul Dvorak
Editorial Director
Windpower Engineering
pdvorak@wtwhmedia.com
@Windpower_Eng

41. #WindWebinar
q This webinar will be available at
www.windpowerengineering.com & email
q Tweet with hashtag #WindWebinar
q Connect with Windpower Engineering & Development
q Discuss this on EngineeringExchange.com
Don’t Forget!

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