Back to the programme printer.gif Print

Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Advanced rotor technologies' taking place on Tuesday, 11 March 2014 at 11:15-12:45. The meet-the-authors will take place in the poster area.

Helge Aagaard Madsen Technical University of Denmark, Denmark
Helge Aagaard Madsen (1) F P Tom Løgstrup Andersen (1) Thomas Schettler (2) Mads Brinch Christensen (3) Michael Schoebel (2) Peter Michels (2) Martin Heisterberg (2) Johnny Egtved Jørgensen (1) Leonardo Bergami (1)
(1) Technical University of Denmark, Roskilde, Denmark (2) Rehau, Rehau, Germany (3) HydratechIndustries, Vrå, Denmark

Printer friendly version: printer.gif Print


Towards an industrial manufactured morphing trailing edge flap system for wind turbines


Several numerical studies in the past 10 years have shown big potentials for load reduction on MW turbines using
distributed control for alleviation of the fluctuating loads along the blade span. However, the requirements by the
wind turbine industry of robust actuator solutions where the strongest specifications mean no metal and electrical
parts in the blades have so far limited the use of the smart blade technology on wind turbines. In the paper the
adaptation of a laboratory manufactured and tested flap system into an industrial manufacturing process is
presented as well a novel testing system.


In 2011 a 3 years research and development project, funded by the Danish funding agency Energistyrelsen, was
initiated with the main goal to transfer the flap system, comprising a morphing trailing edge flap, from laboratory
level to full scale. The industrial project partners Rehau (DE), HydratechIndustries (DK) and Dansk Gummiindustri
(DK) have the important role in the project to develop an industrial manufacturing process of the system and
design it for full scale application. The project coordinator DTU is contributing to the transfer of the technology and
developing a unique outdoor rotating test rig.

Main body of abstract

The flap system, with the first prototype developed back in 2007, comprises a morphing trailing edge flap (15% of
the total chord) manufactured in an elastic material and with voids inside in two layers close to the pressure side
and to the suction side, respectively. The voids can be pressurized with a fluid medium which can be air or an
incompressible fluid. When one of the two layers is pressurized the flap deflects. Thus the flap system is without
mechanical parts.
The industrial production of prototypes has been performed at REHAU in kind of a multi component system
comprising an enforcement structure and two elastic active elements regulated in deformation by a pressurized
fluid medium. Fabrication of the active elements was performed by a continuous thermoplastic extrusion process
in form of a quasi endless 12 chamber hollow profile. For manufacturing the sealed ends of the hollow profiles, a
special method of a contact welding process has been developed.
Different powering concepts for activation of the flaps have been studied by HydratechIndustries and a
pneumatic solution has been selected for initial testing. The first 1m long flap prototype was delivered for
testing at DTU around 1st October 2013. Further testing will be initiated in November 2013 in a novel rotating
test rig based on a 100 kW turbine platform where the normal rotor is replaced by a 10m beam carrying at the
end a blade section of 2m span, 1m chord and the flap system.


It has been demonstrated that the present flap design can be manufactured in an industrial manufacturing
process comprising a continuous thermoplastic extrusion process. In a future mass production the manufacturing
will comprise a 2 components extrusion process in order to build up the enforcement structure as well as the
elastic components simultaneously and inlet for a third component in kind of a solid band with special
characteristics fulfilling the requirements of high cycle stability during operation. Testing the flap system on a 2m
blade section on an outdoor test rig will demonstrate the performance of the system.

Learning objectives
Close cooperation in a project with industrial partners and a university and with funding from the Danish
development and demonstration program EUDP has demonstrated how results of long time research can be
transformed to industry and result in new technology.