Flap Vortex Management by Active Gurney Flaps

Vey, Stefan; Paschereit, C. O.; Greenblatt, David; Meyer, Robert K.

doi:10.2514/6.2008-286

Cited by 10 publications

(9 citation statements)

References 14 publications

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“…The microflap has been studied for active control in several fixed wing applications such as flutter suppression of high aspect ratio flexible wings, 8 aeroelastic control of a blended-wing-body configuration, 9 and wing trailing edge vortex alleviation. [10][11][12] It was found that the deployable microflaps can increase flutter speed of a highly flexible wing by up to 22%. 8 Another study has proposed the use of microflap for control of aeroelastic response at the wing tip of a flexible blended-wing-body configuration.…”

Section: Upstream Separation Bubble Microflap Two Counter-rotating Vomentioning

confidence: 99%

“…8 Another study has proposed the use of microflap for control of aeroelastic response at the wing tip of a flexible blended-wing-body configuration. 9 Recent studies [10][11][12] also suggest that microflaps can be used for wake alleviation by inducing time-varying perturbations that excite vortex instability in the wake. The potential of microflaps with application to active load control in wind turbine blades was also explored computationally and experimentally on representative turbine airfoil sections.…”

Section: Upstream Separation Bubble Microflap Two Counter-rotating Vomentioning

confidence: 99%

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Numerical Evaluation of Microflaps for On Blade Control of Noise and Vibration

Padthe¹,

Liu

Friedmann³

2011

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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Active Gurney flaps, or microflaps, are studied to determine their effectiveness in reducing noise and vibration in rotorcraft, as well as improving rotor performance. The effectiveness of the microflap is examined using a comprehensive rotorcraft simulation code. The aerodynamic properties of the microflap is modeled using a nonlinear CFD based reduced order aerodynamic model that takes into account unsteadiness, compressibility and time varying freestream effects. Active control studies employing microflaps are conducted on a hingeless rotor configuration resembling the MBB BO-105, and various spanwise configurations of the microflaps, including a single, a dual, and a segmented five-microflap configuration are evaluated. Results indicate that the microflap is capable of substantial reductions in blade vortex interaction (BVI) noise ranging from 3-6 dB. Vibration reduction ranging from 70-90% is also demonstrated. The interaction of vibration and noise reduction is also examined, and it was found reduction in one objective is accompanied by an increase in the other, a trend also observed when using other active approaches. Finally, the microflap is considered for combined vibration reduction and performance enhancement at a high speed cruise flight condition. The results clearly indicate that the microflaps are very effective for both noise and vibration reduction in helicopters, and they may also have potential for rotor performance enhancement.

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Section: Upstream Separation Bubble Microflap Two Counter-rotating Vomentioning

confidence: 99%

Section: Upstream Separation Bubble Microflap Two Counter-rotating Vomentioning

confidence: 99%

Numerical Evaluation of Microflaps for On Blade Control of Noise and Vibration

Padthe¹,

Liu

Friedmann³

2011

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

View full text Add to dashboard Cite

show abstract

“…20), and wing trailing-edge vortex alleviation (Refs. [21][22][23]. It was found that the deployable microflaps can increase flutter speed of a highly flexible wing by up to 22% (Ref.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Blade–Vortex Interaction Noise and Vibration Reduction in Rotorcraft Using Microflaps, Including the Effect of Actuator Saturation

Padthe¹,

Friedmann²

2015

j am helicopter soc

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The effectiveness of a sliding microflap to simultaneously reduce rotorcraft vibrations and noise was examined at a descending flight condition of advance ratio 0.15 with significant blade-vortex interactions (BVI). Two configurations, namely dual and a five-microflap configuration, were considered. Closed-loop control studies were conducted on a hingeless rotor configuration resembling MBB BO-105, using the adaptive higher harmonic control algorithm. The performance of the microflap was also compared to a conventional trailing-edge plain flap. The results demonstrate the effectiveness and control authority of the microflap for simultaneous BVI noise and vibration reduction in rotorcraft. Finally, a new saturation control algorithm is developed for limiting the microflap or flap deflections such that the best utilization of on-blade controllers implemented through multiple control surfaces is achieved. The performance of the new algorithm is compared to the existing ones on the dual and five-microflap configurations.

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“…All work presented is based on two experimental investigations: the first was conducted at NASA LaRC (supported by the National Research Council; Greenblatt, 2005Greenblatt, , 2006Greenblatt et al, 2005); and the second was conducted at the Berlin University of Technology in collaboration with the German Aerospace Center (DLR) (Vey et al, 2008). The approach adopted here was to build the concept from the ground up, namely: (a) hypothesis, (b) simple experiment as demonstration of concept, and (c) more complex experiment approaching an airliner configuration.…”

Section: Objective and Scopementioning

confidence: 99%

Active Management of Flap-Edge Trailing Vortices

Greenblatt

Yao

Vey

et al. 2008

4th Flow Control Conference

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The vortex hazard produced by large airliners and increasingly larger airliners entering service, combined with projected rapid increases in the demand for air transportation, is expected to act as a major impediment to increased air traffic capacity. Significant reduction in the vortex hazard is possible, however, by employing active vortex alleviation techniques that reduce the wake severity by dynamically modifying its vortex characteristics, providing that the techniques do not degrade performance or compromise safety and ride quality. With this as background, a series of experiments were performed, initially at NASA Langley Research Center and subsequently at the Berlin University of Technology in collaboration with the German Aerospace Center. The investigations demonstrated the basic mechanism for managing trailing vortices using retrofitted devices that are decoupled from conventional control surfaces. The basic premise for managing vortices advanced here is rooted in the erstwhile forgotten hypothesis of Albert Betz, as extended and verified ingeniously by Coleman duPont Donaldson and his collaborators. Using these devices, vortices may be perturbed at arbitrarily long wavelengths down to wavelengths less than a typical airliner wingspan and the oscillatory loads on the wings, and hence the vehicle, are small. Significant flexibility in the specific device has been demonstrated using local passive and active separation control as well as local circulation control via Gurney flaps. The method is now in a position to be tested in a wind tunnel with a longer test section on a scaled airliner configuration. Alternatively, the method can be tested directly in a towing tank, on a model aircraft, a light aircraft or a full-scale airliner. The authors believed that this method will have significant appeal from an industry perspective due to its retrofit potential with little to no impact on cruise (devices tucked away in the cove or retracted); low operating power requirements; small lift oscillations when deployed in a time-dependent manner; and significant flexibility with respect to the specific devices selected. American Institute of Aeronautics and Astronautics= slot width h G = Gurney flap height relative to the chord l G = Gurney flap span relative to the flap span L f = flap length, from slot to trailing-edge q = free-stream dynamic pressure r = distance measured form the vortex center Re = Reynolds number based on chord-length U j = peak jet slot blowing velocity U = free-stream velocity U,V,W = mean velocities in directions x,y,z X = distance from perturbation to wing trailing-edge x,y,z = coordinates measured from model leading-edge and root (left-hand system) = angle of attack s = static stall angle = flap deflection angle = wavelength = phase shift in degrees = vortex sheet strength, d /dy = bound circulation = rolled-up wake vortex strength = sweep-back angle x = streamwise vorticity, W/ y-V/ z * = indicates control

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Flap Vortex Management by Active Gurney Flaps

Cited by 10 publications

References 14 publications

Numerical Evaluation of Microflaps for On Blade Control of Noise and Vibration

Numerical Evaluation of Microflaps for On Blade Control of Noise and Vibration

Simultaneous Blade–Vortex Interaction Noise and Vibration Reduction in Rotorcraft Using Microflaps, Including the Effect of Actuator Saturation

Active Management of Flap-Edge Trailing Vortices

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