Numerical Investigation on the Aerodynamics of Oscillating Airfoils with Deployable Gurney Flaps

• Published in: AIAA journal 2010-07, Vol.48 (7), p.1457-1469
• Main Authors: Kinzel, Michael P, Maughmer, Mark D, Duque, Earl P. N
• Format: Article
• Language: English
• Subjects: Aerodynamics; Aerospace engineering; Airfoils; Applied fluid mechanics; Assessments; Circulation; Compressibility effects; Computational fluid dynamics; Computational methods in fluid dynamics; Deployable structures; Design optimization; Devices; Effectors; Exact sciences and technology; Flaps; Fluid dynamics; Fundamental areas of phenomenology (including applications); Helicopters; Inertia; Mathematical models; Miniature; Oscillating; Physics; Rotorcraft; Spacecraft; Stall; Trailing edges; Two dimensional; Unsteady; Upstream; Wind tunnels
• ISSN: 0001-1452; 1533-385X
• DOI: 10.2514/1.J050070

To assess their application to rotorcraft, the two-dimensional aerodynamics of deployable Gurney flaps, referred to as miniature trailing-edge effectors, are explored using computational fluid dynamics. These deployable devices have a height of only a few percent of the airfoil chord and deploy normal to the airfoil surface near the trailing edge. Their small size, low inertia, and small added mass make them well suited for deployment in high-frequency applications such as those needed for rotorcraft. A combination of wind-tunnel measurements using airfoils fitted with Gurney flaps and unsteady circulatory theory are used to validate the computational fluid dynamics, and grid and time-resolution studies are used for code verification. Qualitative and quantitative agreement of the effects of a Gurney flap with experiments and theory suggest that the computational fluid dynamics results are valid. These investigations examine the effects of the chordwise positioning and deployment frequency of the miniature trailing-edge effectors. In doing so, their operation on both static and dynamically pitching airfoils is considered. Through these studies, a number of physical insights into miniature trailing-edge effectors and Gurney flap aerodynamics have been obtained. These insights have led to the introduction of a scaling parameter that easily accounts for compressibility effects, an understanding of the aerodynamic consequences due to positioning miniature trailing-edge effectors upstream of the trailing edge, and an assessment on the benefits of using of miniature trailing-edge effectors for active stall alleviation on an airfoil oscillating in pitch. [PUBLICATION ABSTRACT]