Windpower Engineering Webinar - Vortex Generators on Wind Turbines

Copyright 2013 UpWind Solutions, Inc and SMART BLADE GmbH 1
Partnership Profiles
Smart Blade GmbH
German engineering firm established
in 2009, specializing in wind turbine
aerodynamics & blade design
UpWind Solutions, Inc.
North American O&M provider
established in 2007, offering full range
of O&M services and performance
services

Blade Aerodynamics
Root section
Outer section

Design Compromises # 1– Blade Twist

Angle of Attack
Angle of Attack
DragLift
Aerodynamic Stall
Aerodynamic Stall

Betz optimization
Design Compromise # 2 – Chord Width

Design Compromise # 2 – Chord Width

Stall Effects and Cross Flow

Recapturing Lost Energy with VGs
Vortex generators re-energize areas of the
blade that have stalled out
The flow remains attached for higher inflow
angles (stall delay)
Dual benefits: Lift Increase and drag
reduction

Designing the Perfect VG
Development of the optimal VG design and
spacing for high lift-to-drag ratio using wind
tunnel testing
Laser sheet
VG Test Units

Designing the Perfect VG
Analysis of the aerodynamic behavior of VGs
for pre-stall and post-stall conditions
Vortex Cores
Particle Image Velocimetry Results Wind Tunnel Force Balance Results

Every Blade is Unique
Identifying the exact areas where stall
effects are occurring on the blade at various
rotor speeds is essential to maximum ROI
with a VG installation. A one-size-fits all
solution will result in lower PAEY
(Production Annual Energy Yield) increases

Modeling Blade Characteristics

Design – Flow Characteristics
Any VG installation that isn‘t based on a
complete understanding of the flow
characteristics of the blade is missing
valuable power gains

Optimized Installation Design
The flow separation line of a blade
isn‘t straight, neither should a VG
installation
If the orientation of the VGs don‘t change
along the path of the install to account for
cross flow, the quality of vorticies suffer and
drag is increased

VG Design – VG Plastics
Plastic must be proven to survive in UV rich, highly dynamic
environments for 10 + years
The VG should be impact resistant to allow for the installation
to endure:
• Blade access for repair and inspection
• Ice
• Flying debris

VG Design - Adhesives
Adhesive must provide superior durability to match
lifetimes of VG materials
Large climatic (humidity and temperature) installation
envelope necessary for large scale installation
efficiency
Minimum application temp = 40° F / 5° C
Adhesive strength is retained even when installed in
light rain

Installation Using Rope Access
Quality control essential to ensure long
lifetime for the install and long-term
returns on investment
UpWind utilizes a 35 point quality
checklist with photo documentation of
key steps

Installation Using Rope Access
Highly accurate placement ensures
aerodynamic balance of rotor set
Repeatable installation process with
proven 2-10 millimeter accuracy

Proving ROI – Design of Experiment
Turbine A Turbine B
Ref. Turbine (A)
VG Turbine (B)
Annual Energy Production (AEP)
Comparison BEFORE
VG installation
AEP Comparison AFTER
VG installation

Data Post Processing
Turbine A
Turbine B
BEFORE VGs AFTER VGs
Turbine B
Turbine A

AEP Increases
Wind speed
distribution
Turbine A vs
Turbine B
Turbine C vs
Turbine D
- Based on site specific wind distribution data, the AEP
before and after VGs is computed
- Values of AEP increase of 2-3% after a SMART BLADE/
UpWind VG installation are typical for wind turbines in
good condition

Increased Loading Due to VGs?
Unsteady wind turbine loads occur
during normal wind turbine operation
The installation of VGs:
• Avoids stall and reduces the load
variability
• Brings the blade operation closer to
the optimum performance for
which it was designed

Increased Loading Due to VGs?
A full FEA (finite element analysis) based on reference
materials and lamination plan confirmed theoretical
hypothesis that VGs result in an insignificant increase in
the operational loads of the turbine.

Additional Benefits – Noise Reduction
Stall
Noise
Significant
noise source
VGs can
reduce noise
via stall delay

Additional Benefits – Noise Reduction
Aeroacoustic wind tunnel tests performed at various angles and speeds
showed a noise reduction due to VGs

Conclusion – Problem & Solution
Current Turbine Blade Challenges
• Blade aerodynamics (design compromise)
• Aerodynamic stall
• Cross flow dynamics
• Stall and wake losses (separated flow)
Solution – Improved Vortex Generators
• Delay stall
• Increase AEP 2-3%
• Reduce loads during volatile wind speeds
• Corrects for leading edge degradation
• Noise reduction

Conclusion – Customized Process
Process Feature Significance/Value
Non-linear installation contour Accurately traces flow separation
line for optimized performance
Varying VG orientation Correctly oriented VGs minimize
drag and produce highest quality
vortices
Fixed and repeatable
measurement points and use of
installation templates
Optimal and accurate placement of
the VGs to ensure aerodynamic
balance
Self-adhesive tape application Large climatic installation envelope
and technician proof process with
reduced margin for errors

Conclusion
After installing VGs and operating turbines on
multiple wind farms, we have seen an AEP increase
between 2-3%, providing a strong ROI in a short
amount of time for owners
Every day you wait to install VGs, you lose out on
production and ROI
Retail Price: $9,900 per WTG, volume pricing
available for site and fleet wide installations

Windpower Engineering Webinar - Vortex Generators on Wind Turbines

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