An Experimental Investigation into the Effect of Gurney Flaps on Various Airfoils

Cole, Julia A.; Vieira, Bernardo; Coder, James G.; Premi, Amandeep; Maughmer, Mark D.

doi:10.2514/6.2011-1250

Cited by 12 publications

(14 citation statements)

References 8 publications

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“…Wind tunnel tests and CFD simulations (Refs. 161,163,164) indicate that Gurney flaps placed on the lower surface of the airfoil enhance lift and increase the nose-down pitching moment. Despite its small size, the Gurney flap increases the maximum lift coefficient of an airfoil by up to 30% without significant drag penalties (Refs.…”

Section: Evolution and Applications Of Microflapsmentioning

confidence: 98%

On-Blade Control of Rotor Vibration, Noise, and Performance: Just Around the Corner? The 33rd Alexander Nikolsky Honorary Lecture

Friedmann¹

2014

j am helicopter soc

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A concise review of the active control approaches for vibration reduction in rotorcraft is presented. Next, the evolution and status of higher harmonic control and pitch link actuated individual blade control is presented since these serve as the foundations of on blade control. Despite the success of these approaches, demonstrated by both full-scale wind tunnel and flight tests, higher harmonic control and pitch link actuated individual blade control have not managed to earn their way onto a production helicopter. An alternative, on blade control, is defined as a special implementation of individual blade control, where the control surfaces are located on the rotating blade and each blade has its own controller. A concise description of four on blade devices: (1) the actively controlled flap, (2) the active twist rotor, (3) the active tip rotor, and the (4) deployable Gurney flap, or microflap, is presented. An outline of an aeroelastic response modeling capability used to simulate active vibration and noise reduction using flaps or microflaps is presented. The simulation is a thread that links the various parts of the paper. Next, selected results from simulations and scale wind tunnel model tests on active flaps are used to provide insight on the operational and modeling aspects of these systems. Full-scale wind tunnel and flight tests are presented as culmination of the research effort invested in active flap rotors. Then, the evolution and application of the active twist rotor, and deployable Gurney flaps, or microflaps, is presented. The paper concludes with lessons learned and speculation about the potential implementation of on blade control on production rotorcraft.

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Section: Evolution and Applications Of Microflapsmentioning

confidence: 98%

On-Blade Control of Rotor Vibration, Noise, and Performance: Just Around the Corner? The 33rd Alexander Nikolsky Honorary Lecture

Friedmann¹

2014

j am helicopter soc

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“…Measurements also show that the effect of a Gurney flap on lift coefficient is strongly dependent on an airfoil shape [86]. According to Cole et al [86], the lift of aft-loaded airfoils or airfoils with a large separation region (20-30% of the suction surface) does not increase significantly or even decrease when a Gurney flap is added.…”

Section: Gurney Flaps (Classification: Passive Geometric)mentioning

confidence: 99%

“…According to Cole et al [86], the lift of aft-loaded airfoils or airfoils with a large separation region (20-30% of the suction surface) does not increase significantly or even decrease when a Gurney flap is added. The perforation of the Gurney flap has not been found to have any major impact on its efficiency either [83].…”

Section: Gurney Flaps (Classification: Passive Geometric)mentioning

confidence: 99%

“…Better lift augmentation at higher Re [82] 2015 Gurney flap 2%c 255,000; 360,000 35-40% increase in tangential force [84] 2015 Gurney flap Axial pump 0.7-1.4%c 690,000 25% increase in pump head, widened operating range, decreased efficiency [59] 2014 Microtab Wind turbine 0.5-1.2%c 1,000,000 Increased lift and drag [88] 2014 Gurney flap 2%c 1,000,000 Lift augmentation, vibration control [86] 2013 Gurney flap 1.04-2.38%c 1,000,000 Effect on max. lift coefficient depends on airfoil shape [89] 2012 Gurney flap Centrifugal fan 15.9%b 2 30,000-82,000 Pressure ratio and operating range improved at Re < 69,000 [81] 2012 Gurney flap 3-7%c 20,000-35,000 Lift augmentation [90] 2011 Gurney flap Axial fan 10, 20, 30%c < 100,000 Max 18% increase in efficiency with q v,max [83] 2011 Gurney flap 0.7-6%c 254,000 Lift and drag augmentation [91] 2011 Gurney flap 1-6%c 105,000 Wake vortex control [92] 2011 Gurney flap 1.5%c 2,100,000 Vibration reduction [93] 2010 Jet-flap LPT cascade 25,000-200,000 12.5% reduction in solidity [94] 2010 Gurney flap LPT cascade 0.5-3%c 25,000-200,000 12.5% reduction in solidity [8] 2010 Microtab Wind turbine 1-1.5%c 460,000 Max 37% increase in lift [35] 2010 Gurney flap 3000-20,000 Lift augmentation [95] 2010 Gurney flap 40,000-80,000 Lift augmentation [96] 2003 Gurney flap Turbine cascade 0.6-2.7%c 28,000-167,000 Max 9% increase in lift force [85] 2000 Gurney flap 0.5-2%c 1,000,000 Increased lift and drag Outcome: Lift augmentation…”

Section: Gurney Flaps (Classification: Passive Geometric)mentioning

confidence: 99%

See 1 more Smart Citation

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

Tiainen

Grönman

Jaatinen-Värri

et al. 2017

IJTPP

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Abstract:The decrease in the performance of centrifugal compressors operating at low Reynolds numbers (e.g., unmanned aerial vehicles at high altitudes or small turbomachines) can reach 10% due to increased friction. The purposes of this review are to represent the state-of-the-art of the active and passive flow control methods used to improve performance and/or widen the operating range in numerous engineering applications, and to investigate their applicability in low-Reynolds-number centrifugal compressors. The applicable method should increase performance by reducing drag, increasing blade loading, or reducing tip leakage. Based on the aerodynamic and structural demands, passive methods like riblets, squealers, winglets and grooves could be beneficial; however, the drawbacks of these approaches are that their performance depends on the operating conditions and the effect might be negative at higher Reynolds numbers. The flow control method, which would reduce the boundary layer thickness and reduce wake, could have a beneficial impact on the performance of a low-Reynolds-number compressor in the entire operating range, but none of the methods represented in this review fully fulfil this objective.

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“…Overall the lift-to-drag ratio was improved compared to the case with a solid flap of the same height. Recently, Cole et al [12] studied the effect of Gurney flaps of different heights and chordwise locations to five aerofoils using a low-speed, low-turbulence wind tunnel. The results highlighted the fact that the aerofoil shape determines the aerodynamic performance of the aerofoil employing a Gurney flap.…”

mentioning

confidence: 99%

Method for Calculating Rotors with Active Gurney Flaps

Woodgate

Pastrikakis

Barakos

2016

Journal of Aircraft

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This paper builds on the Helicopter Multi-Block version 2 CFD solver of the University of Liverpool and demonstrates the implementation and use of Gurney flaps on wings, and rotors. The idea is to flag any cell face within the computational mesh with a solid, no slip boundary condition. Hence the infinitely thin Gurney can be approximated by "blocking cells" in the mesh. Comparison between thick Gurney flaps and infinitely thin Gurneys showed no difference on the integrated loads, the same flow structure was captured and the same vortices were identified ahead and behind the Gurney. The results presented for various test cases suggest that the method is simple and efficient and it can therefore be used for routine analysis of rotors with Gurney flaps. Moreover, the current method adds to the flexibility of the solver since no special grids are required and Gurney flaps can be easily implemented. Simple 2D aerofoil, 3D wing, and rotors in hover and forward flight were tested with fixed, linearly actuated, and swinging Gurneys, and the ability of the code to deploy a Gurney flap within the multiblock mesh is highlighted.

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An Experimental Investigation into the Effect of Gurney Flaps on Various Airfoils

Cited by 12 publications

References 8 publications

On-Blade Control of Rotor Vibration, Noise, and Performance: Just Around the Corner? The 33rd Alexander Nikolsky Honorary Lecture

On-Blade Control of Rotor Vibration, Noise, and Performance: Just Around the Corner? The 33rd Alexander Nikolsky Honorary Lecture

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

Method for Calculating Rotors with Active Gurney Flaps

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