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Abstract

Rotating blades on helicopters experience reverse flow under high advance ratio conditions. Here, reverse flow is characterized by the flow traveling from the sharp trailing edge to the blunt leading edge. Uncertainty in the blade aerodynamic loads under these conditions has been a limitation during the design of high-speed rotorcraft. In this work, we hypothesize that the reverse flow over a yawed blade includes phenomena similar to the formation of a leading edge vortex on sharp-edged delta wings. Low-speed wind tunnel experiments are reported on a scaled version of a rotor blade in regular and reverse flow over a large range of yaw and moderate ranges of angle of attack. Force measurements indicate a deviation from yawed-wing expectations at high yaw angles. Surface flow visualization via tufts shows the existence of an attached span-wise vortex on the wing.

Keywords

Reverse flow vortex lift yawed wing high advance ratio helicopter

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References

Lozano R, Raghav V and Komerath N. Aerodynamics of a yawed blade in reverse flow. In: Proceedings of ASME 2012 international mechanical engineering congress & exposition, Houston, Texas, 9–15 November 2012.

Perry

. Aerodynamics of the helicopter world speed record. In: The American Helicopter Society 43rd annual forum proceedings, Alexandria, VA: American Helicopter Society, 1987, pp. 3–15.

Walsh

Weiner

Arifian

. High airspeed testing of the Sikorsky X2 Technology™ Demonstrator. In: The American Helicopter Society 67th annual forum proceedings, Alexandria, VA: American Helicopter Society, 2011.

Carter JW, et al. Extreme mu rotor. US Patent 6,986,642, USA, 2006.

Wheatley

Hood

. Full-scale wind-tunnel tests of a PCA-2 Autogiro Rotor, NACA TR 515, 1935.

Charles

Tanner

. Wind tunnel investigation of semirigid full-scale rotors operating at high advance ratios, United States Army Aviation Material Laboratories TR 69-2, 1969.

MacCloud

Biggers

Stroub

. An investigation of full-scale helicopter rotors at high advance ratios and advancing tip Mach numbers , NASA TN D-4632, 1968.

Harris

. Rotor performance at high advance ratio: theory versus test, NASA CR 215370, 2008.

Datta

Yeo

Norman

. Experimental investigation and fundamental understanding of a full-scale slowed rotor at high advance ratios. J Am Helicopter Soc 2013; 58: 1–17.

10.

Yeo

. Investigation of UH-60A rotor performance and loads at high advance ratios. JAircraft 2012; 50: 576–589.

11.

Potsdam M, Datta A and Jayaraman B. Computational investigation and fundamental understanding of a slowed UH-60A rotor at high advance ratios. In: The American Helicopter Society 68th annual forum, Fort Worth, Texas, 1–3 May 2012.

12.

Raghav

Komerath

. An exploration of radial flow on a rotating blade in retreating blade stall. JAm Helicopter Soc 2013; 58: 1–10.

13.

Jacobs

Sherman

. Airfoil section characteristics as affected by variations of the Reynolds number, NACA TR 586, 1937.

14.

Critzos

Heyson

Boswinkle

Jr . Aerodynamic characteristics of NACA 0012 airfoil section at angles of attack from 0 deg to 180 deg, NACA TN 3361, 1955.

15.

Kohlman

Wentz

. Vortex breakdown on slender sharp-edged wings. J Aircraft 1971; 8: 156–161.

16.

Payne

. Structure of leading-edge vortex flows including vortex breakdown, PhD dissertation, University of Notre Dame, 1987.

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