evoblade, a wind energy startup and spin-off of the Institute of Aerospace Technology (IAT) of the University of Applied Sciences Bremen, has developed a retrofittable spoiler for rotor blades – the EvoFlap – with the help of Deutsche Windtechnik and Wirtschaftsförderung Bremen.
“Rotor blades have a significant impact on the technical and economic performance of a wind turbine,” says Dr.-Ing. Frank Kortenstedde, founder and CEO of evoblade. “By developing and optimizing 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.”
The EvoFlap can be adapted to different rotor blade types. The NEG Micon NM 82 turbine – with a rated output of 1.5 MW and a rotor blade length of 40 m – was selected as the basic system for the optimization. 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.
To validate the annual energy output, ROMO Wind was commissioned to carry out independent performance monitoring using iSpin spinner anemometer technology. Measuring the wind speed in front of the turbine is advantageous – 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.
The results of the side-by-side study confirmed the increase in annual energy production (AEP) that had been predicted using simulated data. Recent results also show a 6% 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 – having a positive effect on the service life of the blade.
The EvoFlap can theoretically be installed on all wind turbines that have a slender blade root design. The flow element is suitable as a retrofit solution – or for manufacturers – but needs to be adapted to the individual characteristics of the corresponding blade type.