Experimental Investigation of Gurney Flaps

Maughmer, Mark D.; Bramesfeld, Goetz

doi:10.2514/1.37050

Cited by 86 publications

(62 citation statements)

References 6 publications

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“…Based on the review of flow control mechanisms by Yeo (2008) gurney flaps are generally less than 3% of the wing chord. Previous studies by and Maughmer and Bramesfeld (2008) have concluded that the optimal height for a gurney flap should be close to the boundary layer thickness on the pressure side of the aerofoil. If the gurney flap height is smaller than the boundary layer thickness, then its influence is significantly decreased, while increasing the size of the flap leads to a drag penalty.…”

mentioning

confidence: 98%

Computational aeroelastic analysis of a hovering W3 Sokol blade with gurney flap

Pastrikakis

Steijl

Barakos

et al. 2015

Journal of Fluids and Structures

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This paper demonstrates the potential effect of a gurney flap on the performance of the W3-Sokol rotor blade in hover. A rigid blade was first considered and the calculations were conducted at several thrust settings. The gurney flap was extended from 46%R to 66%R and it was located at the trailing edge of the main rotor blade. Four different sizes of gurney flaps were studied, 2%, 1%, 0.5% and 0.3% of the chord. The biggest flap proved to be the most effective. A second study considered elastic blades with and without the gurney flap. The results were trimmed at the same thrust values as the rigid blade and indicate an increase of aerodynamic performance when the gurney flap is used, especially for high thrust cases. Keywords

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mentioning

confidence: 98%

Computational aeroelastic analysis of a hovering W3 Sokol blade with gurney flap

Pastrikakis

Steijl

Barakos

et al. 2015

Journal of Fluids and Structures

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“…The behaviour of the Gurney flap is related to its length and placement. Studies about the length of the Gurney flap show an increase in drag and pitching moments with increasing lengths [38,53,63,68]. Depending on the application, the Gurney flap length is limited to the point where these disadvantages outweigh its benefits in lift and stall characteristics.…”

Section: The Gurney Flapmentioning

confidence: 99%

“…The Gurney flap modifies the flow at the blade trailing edge and induces a low pressure zone which brings the separation point closer to the trailing edge [53]. The result is an increase of the lift over a large range of angles of attack with a small drag penalty [38,53,59, 68]. Although the Gurney flap induces pitching moment, it provides a beneficial improvement of the efficiency of the rotorblade profile for the hovering situation [68].…”

Section: The Gurney Flapmentioning

confidence: 99%

Smart Actuation for Helicopter Rotorblades

Paternoster¹,

Loendersloot²,

Boer³

et al. 2012

Smart Actuation and Sensing Systems - Recent Advances and Future Challenges

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“…The Gurney flap modifies the flow at the blade trailing edge and induces a low pressure zone which brings the separation point closer to the trailing edge [21]. The result is an increase of the lift over a large range of angles of attack with a small drag penalty [21,22,23,24]. Although the Gurney flap induces a pitching moment, it provides a beneficial improvement of the efficiency of the rotor blade profile for the hovering situation [23].…”

Section: The Gurney Flapmentioning

confidence: 99%

Smart actuation mechanisms for helicopter blades : design case for a Mach-scaled model blade

Paternoster¹

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Today's helicopters are the result of collaborative work in mechanical engineering and aeronautics. The European project "Clean Sky" aims at improving the efficiency and the global transport quality of aircraft. In the field of rotorcraft, the research in this project is currently focussing on active blade systems to adapt the aerodynamic properties of the blade to the local aerodynamic conditions. Fuel-efficiency, reduction of vibration and noise and increase of the helicopter maximum speed are the benefits expected from these new technologies. To envision the implementation of these innovative blade concepts, this thesis investigates the selection process for actuators, the methods to design and optimise actuation systems and the procedures to validate them through simulations and testing.Integrating an actuation system in helicopters is especially difficult because of a combination of challenges. To begin with, these include the tremendous loads due to the rotation of the blade, the limited space available, and constraints regarding durability. Secondly, the impact that the actuation system will have on the rotor blade behaviour has to be taken into account. And lastly, integrating the component inside the actual structure of a rotor blade should be feasible. A system based on piezoelectric actuators provides a potential solution to meet these challenges. A selection process has been established in Chapter 2 to match an actuation technology to application requirements. Among many of the smart blade concepts under development, the active Gurney flap is considered in the framework of the Clean Sky Innovative Technology Development project "Green Rotor Craft", for its potential impact on the blade performance and technology readiness. Actively deploying the Gurney flap on the retreating side of the helicopter increases the lift of the rotorcraft and its overall performances. To validate this technology, numerical studies and wind-tunnel testing on reduced-scale rotor blades are necessary. The procedures detailed in this work are applied to the design of an actuation system to fold and deploy a Gurney flap for a Mach-scaled rotor blade. Additional challenges arose due to the reduction in size: the centrifugal acceleration is increased and the space available inside the blade is drastically reduced.Computational Fluid Dynamic simulations are performed in the first step of the design procedure to obtain the aerodynamic loads on the Gurney flap for various realistic combinations of deployment levels, orientations of the blade in the flow and airspeeds (Chapter 4). Secondly, the design of the actuation mechanism is performed using a two-step approach: (1) computer generated topologies are analysed to find a suitable initial geometry; (2) an optimisation is carried out to maximise the displacement and force of the structure integrating a piezoelectric patch actuator. The resulting structure presents the characteristic shape of a "Z" (Chapter 5). It converts the strains generated by the piezoelectric actuator into rela...

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Experimental Investigation of Gurney Flaps

Cited by 86 publications

References 6 publications

Computational aeroelastic analysis of a hovering W3 Sokol blade with gurney flap

Computational aeroelastic analysis of a hovering W3 Sokol blade with gurney flap

Smart Actuation for Helicopter Rotorblades

Smart actuation mechanisms for helicopter blades : design case for a Mach-scaled model blade

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