7. December 2017
SmartBlades2 - Wind energy research at DLR

First in­no­va­tive DLR ro­tor blade head­ed for load test­ing

Ro­tor blade with bend­ing tor­sion cou­pling
Image 1/4, Credit: DLR (CC-BY 3.0).

Rotor blade with bending torsion coupling

The ro­tor blade con­struct­ed at the DLR site in Stade can adapt to wind con­di­tions.
Smart rotor blades
Smart ro­tor blades
Image 2/4, Credit: DLR (CC-BY 3.0).

Smart rotor blades

The 20-me­tre-long ro­tor blade was con­struct­ed at the DLR Cen­ter for Lightweight-Pro­duc­tion-Tech­nol­o­gy in Stade.
Smart­Blades2: Unit­ing the mould halves
Image 3/4, Credit: DLR (CC-BY 3.0).

SmartBlades2: Uniting the mould halves

The two mould halves are con­struct­ed from dif­fer­ent fi­bre-com­pos­ite ma­te­ri­als.
Smart­Blade2: Con­nect­ing the mould halves
Image 4/4, Credit: DLR (CC-BY 3.0).

SmartBlade2: Connecting the mould halves

The mould halves are firm­ly glued to each oth­er.

  • DLR energy researchers have manufactured the first innovative rotor blade (Smartblade) that adapts to wind conditions using bending torsion coupling
  • In the coming weeks, the rotor blade will undergo load testing at the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Bremerhaven
  • Focus: Renewable energy, wind energy, SmartBlades2

Researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have completed the first innovative rotor blade as part of the SmartBlades2 project. The rotor blade with a length of 20 metres can passively adapt to varying wind conditions using bending torsion coupling. Until the beginning of 2018, the rotor blade will be subjected to numerous load tests at the Fraun­hofer In­sti­tute for Wind En­er­gy and En­er­gy Sys­tem Tech­nol­o­gy (IWES) in Bremerhaven. In the research project Smart­Blades2, industry and research facilities are developing innovative technologies for larger and more powerful wind turbines. The project is supported by the German Federal Ministry for Economic Affairs and Energy (BMWi).

Adapting to wind conditions

During the rotation of a large wind turbine with rotor blades 80 metres and longer, each rotor blade is intermittently positioned close to the ground and a short time later at a height of around 200 metres. Due to the uneven wind distribution between ground level and the top section of the wind turbine, rotor blades are subjected to strong fluctuations in wind load. This results in high stresses for the rotor blade material, particularly when operating at the nominal capacity of the turbine. Additionally, wind turbine operators need to restrict the wind turbines in strong winds and cannot optimally exploit the energy of the wind flow. Rotor blades with bending torsion coupling are able to independently adapt their geometry to the wind conditions. At higher wind speeds the rotor blade twists, thus exposing less contact surface to the wind, which enables the load on the installation to be reduced.

At the Center for Lightweight-Production-Technology (ZLP), located at the DLR site in Stade, scientists from the DLR Institute of Composite Structures and Adaptive Systems have produced a 20-metre-long rotor blade with structural bending torsion coupling. In doing so, the materials of the blade (glass-fibre reinforced plastic, wood and plastic foam) are placed in such a way that under wind load the blade not only bends backwards, but above all twists. "Because of the innovative structure the rotor blades are more flexible, at the same time allowing them to be lighter and less massive. Particularly for very large wind turbines, less weight is a great benefit and additionally makes transportation and assembly easier," emphasises Zhuzhell Montano Rejas, Project Manager of SmartBlades2 at the DLR Institute of Composite Structures and Adaptive Systems.

Tests under extreme loads

From December onwards, the load tests will be conducted on a rotor blade test rig at the Fraunhofer IWES in Bremerhaven. Here, the load-bearing capacity of the rotor blade will be tested under extreme loads and under normal operating conditions in order to determine the blade properties and their deformation behaviour. The scientists pay special attention to whether bending and torsion of the rotor blade optimally complement one another. The scientists have integrated measuring sensors inside the rotor blade for accurate data recording during the load tests. This allows them to observe structural and material deformations. Once a sufficient load-bearing capacity has been confirmed, within the coming year the scientists will produce a complete three-blade rotor with the same dimensions, which they will subject to open air wind turbine testing under realistic load and weather conditions at the US Na­tion­al Re­new­able En­er­gy Lab­o­ra­to­ry (NREL).

The SmartBlades2 project – intelligent rotor blades

Bending torsion coupling is one of many technologies to be developed further in the SmartBlades2 research project. In total, 11 partners from the Research Alliance Wind Energy (DLR, For­Wind Hannover and ForWind Oldenburg, Fraunhofer IWES) and industry (GE Global Research, Henkel AG & Co. KGaA, Nordex En­er­gy, SSB Wind Sys­tems GmbH & Co. KG, Su­zlon En­er­gy Ltd. and WRD Wobben Research and Development GmbH) are working together on innovative rotor blades. The project is supported by the BMWi with an amount of 15.4 million euro. The aim of the research work is realising larger and more efficient rotors that allow greater exploitation of wind energy and increase the competitiveness of German companies in the wind-energy industry.

Further technologies investigated in the project are adaptive trailing edge flaps and leading edge slats. Both concepts come from aviation and are comparable to the flaps on aircraft wings. In addition, researchers are working on the further development of selected methods and technologies such as the aerodynamic behaviour of rotor blades and control of the entire system.

  • Dorothee Bürkle
    Ger­man Aerospace Cen­ter (DLR)
    Me­dia Re­la­tions, En­er­gy and Trans­port Re­search
    Telephone: +49 2203 601-3492
    Fax: +49 2203 601-3249

  • Dr.-Ing. Jan Teßmer
    Ger­man Aerospace Cen­ter (DLR)
    En­er­gy Pro­gramme Di­rec­torate
    Co­or­di­na­tion Wind En­er­gy Re­search
    Telephone: +49 531 295-3217
    Fax: +49 531 295-2838
    Lilienthalplatz 7
    38108 Braunschweig
  • Zhuzhell Matilde Montano Rejas
    Ger­man Aerospace Cen­ter (DLR)

    DLR In­sti­tute of Com­pos­ite Struc­tures and Adap­tive Sys­tems
    Telephone: +49 53 12952-642
    Linder Höhe
    51147 Köln

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