evoblade and Deutsche Windtechnik develop trailing edge spoilers for rotor blades – study confirms flow improvement, load reduction and positive effect on entire service life

The wind energy start-up evoblade, a spin-off of the Institute of Aerospace Technology (IAT) of the University of Applied Sciences Bremen, has developed a retrofittable spoiler for rotor blades with the help of Deutsche Windtechnik and Wirtschaftsförderung Bremen. The results of a side-by-side study of testing and optimising the EvoFlap now confirm that installing the spoiler can improve the aerodynamic flow in the area of the blade root, resulting in improved efficiency and performance of the system.

"Rotor blades have a significant impact on the technical and economic performance of a wind turbine,"
said Dr.-Ing. Frank Kortenstedde, founder and CEO of evoblade. "By developing and optimising a
retrofittable flow element, we wanted to achieve a technical and economic improvement in the
properties of existing systems that leverages the advances in technical understanding." Matthias Brandt,
Director of Deutsche Windtechnik AG, added: "Even though retrofitting flow elements is not always an
option, and the initial design and features of turbines are up to the system manufacturers, we are still very
happy to participate in and support research projects like this that look at technologies of the future. The
results are moving in the right direction and are helping the entire industry!"

Side-by-side study design with iSpin performance monitoring
The EvoFlap can be adapted to different rotor blade types. The NEG Micon NM 82 turbine type with a
rated output of 1.5 MW and a rotor blade length of 40 m was selected as the basic system for the
optimisation. The flow element was developed using the GFRP sandwich technique and has an overall
length of 10 m. It is divided into seven segments to allow assembly directly on an installed rotor blade.
"The blade does not have to be removed from the hub to allow EvoFlap to be installed, and this reduces
the amount of work and costs," Frank Kortenstedde emphasised. "Also, the blade structure is not
damaged by gluing the segments onto it, and the EvoFlap blends harmoniously with the blade design." To
validate the annual energy output, the company ROMO Wind was commissioned to carry out independent
performance monitoring using iSpin spinner anemometer technology. Measuring the wind speed in front
of the turbine has the advantage that the reference wind speed is measured directly and undisturbed. In
addition to the test system, a second (adjacent) turbine of the same type was equipped with iSpin
technology as a reference system.

Six percent additional yield and positive effect on service life
The results of the side-by-side study (project duration 08/2015 - 03/2019) confirmed the increase in AEP
(annual energy production) that had been predicted using simulated data. Recent results also show a six
percent increase in AEP with an average annual wind speed of 7 m/s. In addition to increasing the yield, it
was demonstrated that the EvoFlap also increases the bending and torsion strength of the rotor blade,
and this has a positive effect on the service life of the blade. "Depending on the useful life of the EvoFlap,
a possible extension of 1.2 to 2.6 years beyond the maximum service life of 20 years can be achieved,"
Frank Kortenstedde explained. "A very high level of technology transfer has been achieved. Retrofitting
such large-scale flow elements is currently the absolute exception. Nevertheless, this research project
shows significant potential positive effects."

The EvoFlap can theoretically be installed on all wind turbines that have a slender design in the area of the
blade root. The flow element is suitable as a retrofit solution or for manufacturers of wind turbines, but it
needs to be adapted to the individual characteristics of the corresponding blade type.

About evoblade
evoblade is a spin-off of the Institute of Aerospace Technology. The close cooperation with the University
of Applied Sciences Bremen and its research activities is the foundation of its competence, services and
products. evoblade offers aerodynamic optimisation of rotor blades of wind turbines using the trailing
edge spoiler EvoFlap. This patented technology can achieve a significant increase in the efficiency of wind
turbines. The EvoFlap spoiler is individually developed and adapted for each rotor blade type to achieve
the best performance improvement.

Contact for evoblade: Frank Kortenstedde
More information about evoblade and images for free editorial use: evoblade.de/projekte

About ROMO Wind
ROMO Wind is a technology and service company in the wind industry with headquarters located in
Switzerland and branch offices in Germany, Denmark, France, Italy and Spain. ROMO Wind is specialised in
precisely determining the wind conditions at wind turbines independently of manufacturers and
optimising the productivity of wind turbines as well as minimising loads based on the data obtained. For
this purpose, the company uses the patented iSpin® spinner anemometer technology, which is already
used in more than 1.200 wind turbines, more than 70 different turbine types (onshore and offshore) and
in more than 20 countries.

Contact for ROMO Wind: Marcus Müller
More information on iSpin technology and images for free editorial use: www.romowind.com

About Deutsche Windtechnik
Bremen-based Deutsche Windtechnik AG offers a single-source full technical maintenance package for
wind turbines in Europe, the USA and Taiwan. The company operates both onshore and offshore. More
than 5,800 wind turbines are serviced worldwide, by over 1,800 employees, under permanent
maintenance contracts (basic and full maintenance). Its system engineering focuses on Vestas/NEG Micon,
Siemens/AN Bonus, Nordex, Senvion, Fuhrländer, Gamesa and Enercon turbines.

Deutsche Windtechnik AG
Stephanitorsbollwerk 1, 28217 Bremen
Phone +49 421 691 05-0, Fax +49 421 691 05-499