the reliability of rotor blades - enerconresponse.enercon.de/files/20161117_a hoffmann_reliability...
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AGENDA
1. GENERAL REQUIREMENTS OF ROTOR BLADES FOR WIND ENERGY CONVERTERS
2. ENERCON´S STRUCTURAL DESIGN & PRODUCT PHILOSOPHY
3. MATERIAL-, COMPONENT-, AND FULL-SCALE-BLADE-TESTING
4. BLADE DE-ICING-SYSTEM
5. EROSION PROTECTION
6. LIGHTNING PROTECTION
7. TRAILING EDGE SERRATIONS (TES)
TO REDUCE TRAILING EDGE NOISE
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GENERAL REQUIREMENTS OF ROTOR BLADES
• Long-Life-Cycle, Operation up to 30 years ,
> 10^9 Load-Cycles, technical availability > 97%
• Easy and cheap design to manufacture
• Light-weight structure
• Easy transport (truck, train, ship)
• Easy and quick erection (e.g. single-blade installation)
• Low maintenance effort (e.g. high erosion-resistance)
• Low sound power level
• Lightning protection & rotor blade de-icing system
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ENERCON´S STRUCTURAL DESIGN & PRODUCT PHILOSOPHY
PEELING-STRESS
• Best possible “fail-safe” structure
• Only chamfered bonding line flanges
• For blades longer than 15m, always a double-shear-web-
design is realised
• Highest quality standards in blade productions
SHEAR-WEBS
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CENTRIFUGAL
FORCE SUPPORT
TRANSVERSE
BULKHEAD
NO-BONDING-LINE
CONTOUR WEDGE
PARTING-LINE /
NO AERODYNAMIC SHORT-CIRCUIT
ENERCON´S STRUCTURAL DESIGN & PRODUCT PHILOSOPHY
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MATERIAL-, COMPONENT- AND FULL-SCALE-BLADE-TESTING
Full-Scale-Blade-Testing static and
fatigue according to IEC 61400-23
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1. Static extreme loading in
at least four main-directions
(including Load-Safety-
Factor of approx. 135% plus
110% Test-Factor)
2. Dynamic loading in flap-
and edge direction with at
least 1 million up to 5 million
cycles and a dynamic
overloading of approx. 30%
3. Residual Strength Test
with 10% lower static
extreme loading than first
static tests
MATERIAL-, COMPONENT- AND FULL-SCALE-BLADE-TESTING
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ENERCON-Solution: Air-Blade-Heating in Rotor-Blades
DEFLECTION BOW
SHEAR-WEB DROP
BLADE DE-ICING-SYSTEM
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EROSION PROTECTION
ENERCON´S NEW EROSION PROTECTION SYSTEM:
Impact Absorption Layer consists of two layers which are bonded
together by a vulcanisation process.
a. Wear-resistant UHMWPE layer (Ultra high molecular weight
Polyethylene)
b. EPDM (Soft Rubber) layer (Ethylene Propylene Diene Monomer)
for safe connection to the fibre reinforced blade structure.
Both layers in combination provide highest resistance behaviour
against erosion.
The soft EPDM layer has a shock-absorbing effect and the outer
UHMWPE film is very resistant to erosion.
• Solution for mass production
• Retrofit solution
• Easy to repair, e.g. due to damage during transport
UHMWPE
EPDM
GFRP ROTOR BLADE
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LIGHTNING PROTECTION
LIGHTNING CURRENT PARAMETERS Symbol Unit LPL I LPL I+
Peak current I kA 200 300
Short stroke charge Qshort C 100 150
Specific energy W/R MJ/Ω 10 22,5
Time parameters of short stroke T1/T2 µs/µs 10/350
Long stroke charge Qlong C 200 1000
Time parameter of long stroke Tlong s 0,5
Flash charge Qflash C 300 1150
LIGHTNING
ATTACHMENT
POINTS
Lightning protection concept according to latest research
• Defined lightning attachment points to conduct lightning current safely to ground
• Tested according to latest standards with lightning parameters up to 5 times
higher than required for Lightning Protection Level I (LPL I, highest standardized
Lightning Protection Level)
• LPL I+ is defined by ENERCON based on LPL I with increased lightning
current parameters
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• Turbulent flow at the trailing edge
causes pressure fluctuation which
emits noise
• New geometry at the trailing edge
reduces the turbulent wake effects
• Result = Reduction of aerodynamic
noise
• Position and angle of TES directly out
of the mould for reproducible quality
TRAILING EDGE SERRATIONS (TES) TO REDUCE TRAILING EDGE NOISE
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