Self-Actuating Flaps for wind turbines: Boosting the Efficiency of Wind Turbines with Self-Actuating Flaps


Deutsche Bundesstiftung Umwelt

ForWind, Wind-Tuning-Systeme Ingenieurbüro Röhm WTS

Duration: 11/2017 – 07/2018


In wind turbines, the air flows along the rotor blades and generates lift. However, in unfavorable conditions, the current detaches from the rotor blade. This phenomenon is known as “stall” and reduces the turbine’s performance.

In order to equip wind turbines against this effect, scientists at Fraunhofer IWES are collaborating with industry and research partners to test the use of mechanisms known as self-actuating flaps. The flaps attached to the suction side of the blade profile open automatically just before the current detaches. They ensure higher lift and reduce the air resistance. In terms of the turbine’s operation, this translates to improved performance and thus a higher energy yield. In addition, delayed detachment of the current can also result in lower loads, which extends the service life of the system overall.

Further advantages: The self-actuating flaps can be fitted on old or new turbines without the need for any adjustments to the existing blade structure. An additional base element affixed to the trailing edge contributes to reducing noise pollution, which can in turn lead to better acceptance of wind turbines.

Self-actuating flaps have already been simulated and tested on glider profiles. IWES researchers are now performing 2D flow simulations in cooperation with the project partners in order to investigate the benefits of self-actuating flaps in wind turbines. This will be followed by wind tunnel tests and computational estimations of yield increases and load reductions for complete 3D blades.