Investigation of the load reduction potential of two trailing edge flap controls using CFD

Wind Energy ◽  
2010 ◽  
Vol 14 (3) ◽  
pp. 449-462 ◽  
Author(s):  
Joachim Heinz ◽  
Niels N. Sørensen ◽  
Frederik Zahle
Keyword(s):  
Reduction Potential ◽  
Load Reduction ◽  
Trailing Edge ◽  
Trailing Edge Flap

Design and Experimental Investigation of a Flexible Trailing Edge for Wind Energy Turbine Blades

2020 ◽  
Author(s):  
Martin Pohl ◽  
Johannes Riemenschneider ◽  
Hans Peter Monner
Keyword(s):  
Wind Tunnel ◽  
Wind Energy ◽  
Turbine Blades ◽  
Free Field ◽  
Electric Energy ◽  
Outer Region ◽  
Load Reduction ◽  
Bending Moments ◽  
Trailing Edge ◽  
Trailing Edge Flap

Abstract The demand of affordable, renewable electric energy is still increasing. Wind energy is seen as one of the most promising resources for future electric energy supply. To reduce the cost of wind energy the dimensions of wind energy turbines are still increasing. This leads to higher power output due to the larger rotor diameters, but also due to the higher wind speeds above the boundary layer. This increase in rotor diameter is achieved at the expense of much higher structural loads especially in the rotor blade root. These loads consist of bending moments, that are mainly caused by gravity, wind shear, gusts and the tower influence to the blade. A reduction of these root bending moments would allow a further increase of the rotor diameter, a longer lifetime or a lighter design and therefore be advantageous for the turbine. Load reduction can be achieved by using a trailing edge flap at the outer region of the blade, comparable to control surfaces of aircraft. This trailing edge is capable of moving several times per blade revolution and allows the manipulation of the flow to alleviate changes in the aerodynamic loading. In contrast to aircraft, sealing against environmental media, such as rain, dust, insects and so on is much more important to allow a high lifetime and low maintenance effort. Therefore, a flexible and gapless morphing trailing edge has been designed within the SmartBlades projects at the German Aerospace Center (DLR) for the mentioned purpose. Based on this design, a demonstrator was built, which was tested in a wind tunnel and on a rotational test site for its performance. The paper will present the approach beginning with some design and modeling considerations of the flexible trailing edge and the demonstrator, which was used for testing. Main focus of the paper is the presentation of results obtained from a wind tunnel experiment at Oldenburg University and the rotational experiment at the field research site of the Technical University in Denmark (DTU). In these experiments, the effectiveness of the trailing edge flap could be demonstrated in the wind tunnel as well as in free field. Based on pressure taps and force sensors, the change in the lift of the airfoil due to the deflection of the flexible trailing edge was measured and the resulting polars are shown in this paper. Furthermore, the result of different simple control strategies for the trailing edge in terms of load reduction at the rotating test rig will be presented.

Performance enhancement evaluation of an actuated trailing edge flap

2001 ◽  
Vol 105 (1049) ◽  
pp. 391-399 ◽  
Author(s):  
W. Chan ◽  
A. Brocklehurst
Keyword(s):  
Adverse Effect ◽  
Performance Enhancement ◽  
Optimal Configuration ◽  
Analytical Evaluation ◽  
Trailing Edge ◽  
Design Constraints ◽  
Flight Condition ◽  
Trailing Edge Flap

Abstract An analytical evaluation of the performance enhancement due to a servo-actuated trailing edge flap was carried out using the coupled rotor-fuselage model (CRFM). The performance enhancement from a trailing edge flap is achieved by introducing effective camber around the azimuth for a nominal aerofoil. An investigation on the best combination of flap parameters, namely the span, position, chord and deflection was carried out in order to identify an optimal configuration within given design constraints. The effects on vibratory control loads over a range of speed for a flap of 10% span, 20% chord, actuated at once per rev has expanded the retreating blade envelope for a Lynx aircraft by some 20kt. The flap hinge load was also examined and it was found not to be excessive. It was also confirmed that an actuated trailing edge flap does not have adverse effect on the pilot's control inputs to trim to a particular flight condition. This paper will discuss the aerodynamic enhancements derived from the application of the trailing edge flap and present conclusions drawn from this study.

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