Effects of tilting rate variations on the aerodynamics of the tilting ducted fans mounted at the wing tips of a vertical take-off and landing unmanned aerial vehicle

Abstract

Tilting ducted fans mounted at the wing tips of vertical take-off and landing unmanned aerial vehicles define new applications for these types of aerial vehicles. This new configuration gives vertical take-off and landing unmanned aerial vehicles the ability to hover like helicopters and fly forward like airplanes, which results in using any arbitrary location for take-off and landing combined with increasing range and speed. Furthermore, generating additional lift by using asymmetrical shape for the external body of the ducted fans can lead to reducing the wing area and related overall drag, which results in saving more energy. The transition between cruise mode and hovering can be done by choosing different tilting rates, which can produce instabilities in the aerodynamics of the tilting ducted fans mounted at the wing tips of the vertical take-off and landing unmanned aerial vehicles. This research provides the computational fluid dynamics simulations to investigate these instabilities and compare them for two different ducted fans. “Actuator disk model” combined with the assumption of “constant delivered power” to the propeller were used successfully to calculate the induced velocity to the rotor plane of the ducted fan in the computational fluid dynamics simulations. The effects of the flow separation on the aerodynamic coefficients were discussed and compared for both symmetrical and asymmetrical ducted fans in different tilting rates.

Keywords

Tilting ducted fan vertical take-off and landing unmanned aerial vehicle computational fluid dynamics modeling

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References

McCormick

. Aerodynamics of V/STOL flight, Mineola, NY: Dover Publications, 1999.

Martin P and Tung C. Performance and flowfield measurements on a 10-inch ducted rotor VTOL UAV. In: 60th annual forum of the American Helicopter Society, Baltimore, MD, USA, 7–10 June 2004.

Fleming J, Jones T, Gelhausen P, et al. Improving control system effectiveness for ducted fan VTOL UAVs operating in crosswinds. In: 2^nd AIAA unmanned unlimited systems, technologies, and operations-aerospace, San Diego, CA, USA, 15–18 September 2003.

Graf W, Fleming J and Ng W. Improving ducted fan UAV aerodynamics in forward flight. In: 46th AIAA aerospace sciences meeting and exhibit, Reno, NV, USA, January 2008.

Akturk A, Shavalikul A and Camci C. PIV measurements and computational study of a 5-inch ducted fan for V/STOL UAV applications. In: 47th AIAA aerospace sciences meeting and exhibit, Orlando, FL, January 2009.

Camci

Akturk

. Double ducted fan. The Pennsylvania State University, A technology description document. 2010.

Mort KW and Gamse B. A wind tunnel investigation of a 7-foot diameter ducted propeller. Technical Report, NASA TND-4142, 1967.

Yaggy PF and Mort KW. A wind-tunnel investigation of a 4-foot-diameter ducted fan mounted on the tip of a semispan wing. Technical Report, NASA TND-776.

Mort KW and Yaggy PF. Aerodynamic characteristics of a 4-foot-diameter ducted fan mounted on the tip of a semispan wing. Technical Report, NASA TND-1301, 1962.

10.

Weir RJ. Aerodynamic design consideration for a free flying ducted propeller. In: AIAA atmospheric flight mechanics conference, Minneapolis, MN, U.S.A, 1988.

11.

Abrego AI and Bulaga RW. Performance study of a ducted fan system. In: AHS aerodynamics, aeroacoustic, test and evaluation technical specialist meeting, San Francisco, CA, USA, January 2002.

12.

Gress GR. Lift fans as gyroscopes for controlling compact VTOL air vehicles: Overview and development status of oblique active tilting. In: 63rd annual forum of the American Helicopter Society, Virginia Beach, VA, USA, 1–3 May 2007.

13.

Raeisi

Alighanbari

. Simulation and analysis of flow around tilting asymmetric ducted fans mounted at the wing tips of a VTOL UAV. J Aerosp Eng 2017.

14.

Leishman

. Principles of helicopter aerodynamics, 2nd ed. London: Cambridge University Press, 2006.

15.

Somers DM and Maughmer MD. Theoretical aerodynamic analyses of six airfoils for use on small wind turbines. Subcontractor Report, 2003.

16.

ANSYS Fluent tutorial, 2013.

17.

Ko A, Ohanian OJ and Gelhausen P. Ducted fan UAV modeling and simulation in preliminary design. In: AIAA modeling and simulation technologies conference and exhibit, Hilton Head, SC, USA, August 2007.

18.

Pereira JL. Hover and wind tunnel testing of shrouded rotors for improved micro air vehicle design. PhD Dissertation, University of Maryland, USA, 2008.

19.

Bearman

. Vortex shedding from oscillating bluff bodies. Annu Rev Fluid Mech 1984; 16: 195–222.

20.

Williamson

CHK

Govardhan

. Vortex-induced vibrations. Annu Rev Fluid Mech 2004; 36: 413–455.