Alleviation of Airfoil Dynamic Stall Moments via Trailing-Edge Flap Flow Control

Feszty, Dániel; Gillies, Eric A.; Vezza, M.

doi:10.2514/1.853

Cited by 49 publications

(37 citation statements)

References 20 publications

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“…For the steady simulations, the solver output loads are directly used in Eq. (22), which has no imaginary terms. C l K p and C m K p are the KS aerodynamic loads to be computed by the optimization algorithm according to the free parameters in p. Depending on the sectional degree of freedom under consideration, different sets of free parameters are selected among all those of the KS formulation.…”

Section: Reduced-order Model For An Airfoil Equipped With the L-tabmentioning

confidence: 97%

“…Several authors worked on the application of movable trailing-edge flaps on rotorcraft blades for vibratory load control (see [16][17][18][19][20]) and for the mitigation of negative effect associated with dynamic stall (see [21][22][23]). Because a GF has considerably less inertia than a traditional flap, smaller forces are expected to be required to actuate the system.…”

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confidence: 99%

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Linear Reduced-Order Model for Unsteady Aerodynamics of an L-Shaped Gurney Flap

Motta

Quaranta

2015

Journal of Aircraft

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Analysis of ballistic capture orbits in Sun–planet systems is conducted in this paper. This mechanism utilizes purely gravitational forces, and may occur in non-Keplerian regimes. Ballistic capture orbits are generated by proper manipulation of sets of initial conditions that satisfy a simple definition of stability. Six Sun–planet systems are considered, including the inner planets, Jupiter, and Saturn. The role of planets orbital eccentricity, their true anomaly, and mass ratios is investigated. Moreover, the influence of the post-capture orbit in terms of inclination and orientation is also assessed. Analyses are performed from qualitative and quantitative perspective. The quality of capture orbits is measured by means of the stability index, whereas the capture ratio gives information on their statistical occurrence. Some underlying principles on the selection of the dynamical model, the initial true anomaly, and inclination are obtained. These provide a reference for practical cases

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Section: Reduced-order Model For An Airfoil Equipped With the L-tabmentioning

confidence: 97%

mentioning

confidence: 99%

Linear Reduced-Order Model for Unsteady Aerodynamics of an L-Shaped Gurney Flap

Motta

Quaranta

2015

Journal of Aircraft

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“…Many attractive solutions for improving the helicopter performance and alleviate the detrimental effects of dynamic stall 1 were investigated as, for instance, the use of air-jet vortex generators, 2,3 plasma actuators 4 or trailing edge flaps. 5 Among these studies, the interest about the effects of a Gurney flap 6 on rotor blades 7 has recently grown, as demonstrated by the several works about the study of the potential effect of an active deployable Gurney flap (see, for instance, Refs. [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of a trailing edge L-shaped tab on a pitching airfoil in deep dynamic stall conditions

Zanotti

Grassi

Gibertini

2013

Proceedings of the Institution of Mechanical Engineers, Part G:

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An L-shaped tab was tested at the trailing edge of an oscillating airfoil to evaluate its effects on blades aerodynamic performance. The tests were conducted on a NACA 23012 pitching airfoil in deep dynamic stall conditions with the L-shaped tab fixed in two different positions. When deployed the tab is attached to the airfoil upper surface so that the end prong protrudes at the airfoil trailing edge. In retracted position the tab features an angle of 9.1 with the airfoil upper surface, since its prong tip touches the airfoil trailing edge. The airloads time histories during a pitching cycle were evaluated by pressure measurements carried out on the airfoil midspan contour. The phase-averaged flow field at the trailing edge region was investigated by means of particle image velocimetry to evaluate the detailed flow physics involved in the use of the device. The experimental results indicate that the use of such a pivoting L-shaped tab can introduce similar effects to those that can be obtained by the use of an active Gurney flap. Thus, the L-shaped tab can be considered an attractive device due to its easier integration on helicopter blades.

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“…As an addition to the Smart Spring, a suitably actuated trailing-edge flap could perform flow control by alleviating the negative effects of dynamic stall on the retreating side of the blade. This would reduce the vibration excitation loads at the origin of the phenomena [8]. In [8], it was shown that the required size of such a flap is relatively small, facilitating its integration within the blade, with the request of very small actuator loads.…”

Section: Introductionmentioning

confidence: 98%

“…This would reduce the vibration excitation loads at the origin of the phenomena [8]. In [8], it was shown that the required size of such a flap is relatively small, facilitating its integration within the blade, with the request of very small actuator loads. Finally, it has been demonstrated in separate studies that optimization of the blade anhedral tip angle can alleviate BVI at a fixed rotor attitude, by displacing the trajectory of the vortices that are shed at the tip of the blade [9].…”

Section: Introductionmentioning

confidence: 98%

Experimental Investigation on Modal Signature of Smart Spring/Helicopter Blade System

Coppotelli

Marzocca

Ulker

et al. 2008

Journal of Aircraft

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To achieve efficient attenuation of noise and vibration characteristics within the helicopter environment, solidstate actuators are seen as one of the most promising smart technologies. The Smart Hybrid Active Rotor Control System project is expected to demonstrate the ability of smart structure systems, employing multiple active material actuators, sensors, and closed-loop controllers, to reduce simultaneously rotorcraft vibration and noise. Within this project, piezoceramic elements were used as actuators to vary the dry friction and the stiffness of the whole helicopter blade system. This active control concept, named Smart Spring, originated a prototype used to demonstrate the ability to attenuate vibrations. Before testing the Smart Hybrid Active Rotor Control System in operative conditions, the dynamic properties of the Smart Spring installed on a nonrotating helicopter blade are investigated. The effects of the Smart Spring actuator on the modal properties are studied through experimental activities carried out at Carleton University. Furthermore, the capability of the Smart Spring to change the dynamic behavior of the helicopter blade is demonstrated by analyzing the shifts in the modal parameters. Finally, a beam finite element model of the blade, with stiffness and mass properties tuned to the experimental structure, is presented.

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Alleviation of Airfoil Dynamic Stall Moments via Trailing-Edge Flap Flow Control

Cited by 49 publications

References 20 publications

Linear Reduced-Order Model for Unsteady Aerodynamics of an L-Shaped Gurney Flap

Linear Reduced-Order Model for Unsteady Aerodynamics of an L-Shaped Gurney Flap

Experimental investigation of a trailing edge L-shaped tab on a pitching airfoil in deep dynamic stall conditions

Experimental Investigation on Modal Signature of Smart Spring/Helicopter Blade System

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