Fluid Mechanics & Aerodynamics

Fluid Mechanics & Aerodynamics

Investigating Effects of Sinusoidal Leading Edgeon a Lambda-wing UAV at Pre-stall Angles

Document Type : Original Article

Authors
Amir Hosseinikargar 1
Mohammad Hassan javareshkian 2
Afshin Madani 3
1 Master's Degree, Ferdowsi University of Mashhad, Mashhad, Iran
2 Professor, Ferdowsi University of Mashhad.. Mashhad. Iran
3 Master's student, .Ferdowsi University of Mashhad. Mashhad. Iran
Abstract
Using a sinusoidal leading edge on a wing effectively controls flow and prevents flow separation from the wing surface. This study investigates the aerodynamic effects of introducing a sinusoidal leading edge on a lambda-shaped flying-wing UAV while keeping the wing area constant. The analyzed geometry features a wing with a 56-degree sweep angle and a -3-degree twist. The research employs numerical simulations using the Reynolds-averaged Navier–Stokes (RANS) equations solved through the finite volume method. The simulation process was validated with experimental data for angles of attack ranging from -5 to 20 degrees. Two key variables, the sinusoidal wave's amplitude and wavelength, were derived from previous experiments on similar UAVs. These parameters were selected to optimize the wing’s aerodynamic characteristics and improve vortex formation locations, especially at high angles of attack. The results indicate that applying a sinusoidal leading edge improves the lift-to-drag ratio by approximately 20% at attack angles between 5 and 15 degrees, leading to greater range and reduced fuel consumption. This research provides practical insights for the design and performance enhancement of UAVs. Additionally, the study shows that vortices form from each sinusoidal crest in a lambda wing with a sinusoidal leading edge, unlike flat-edged wings where vortices originate at the apex. This change in vortex structure may enhance lateral flow reattachment and delay flow separation at high angles of attack.
Keywords
Sinusoidal Leading Edge Flying Wing Numerical Simulation Lift
to
Drag Ratio

Smiley face

[1]     Myhra, D., “The Horten Brothers and Their All-Wing Aircraft”, Schiffer Military/Aviation History, Schiffer Publ., Atglen, PA, 1998.
[2]     Anderson, J.D., “Aircraft Performance & Design”, McGraw-Hill Education, 1st Edition, 1998.
[3]     Hamunpeyma, D., Alighanbari, A., “Non-uniform and Partial Coating of an Aircraft for Achievement of the Minimum Radar Cross Section with the Minimum Weight of Absorbent”, Journal of Radar, Vol. 5, No. 2, 2017 (In Persian).https://dor.isc.ac/dor/20.1001.1.23454024.1396.5.2.3.9
[4]     Qu, X., Zhang, W., Shi, J., and Lyu, Y. “A novel yaw control method for flying-wing aircraft in low speed regime”, Aerosp Sci Technol. Vol. 69, pp. 636–649, 2017.
[5]     Dehghan Manshadi, M., Ilbeigi, M., Bazazzadeh, M., and Vaziri, M.A., “Experimental Study of Aerodynamic Coefficients of a Lambda-Shaped Flying Aircraft Model by Changing the Backward Angle of the Wing Attack Edge”, Journal of Modares Mechanical Engineering, Vol. 16, No. 5, pp. 303–311, 2016 (In Persian).
[6]     Anderson, Jr. J.D. “Fundamentals of aerodynamics”, McGraw-Hill Education, University of Maryland, Penn Plaza, New York, 2010.
[7]     Ko, A., Chang, K., Sheen, D.J., Jo, Y.H., and Shim, H.J. “CFD Analysis of the Sideslip Angle Effect around a BWB Type Configuration”   Int J Aerosp Eng. vol. 2019, 2019.
[8]     Ramezanizadeh, M., and Mohammadi, A., “Numerical Investigation of Delta Wings Leading Edge Configuration Effects on the Flow Behavior Using Large Eddy Simulation Approach”, Journal of Fluid Mechanics and Aerodynamics, Vol. 3, No. 3, pp. 49–60, 2014 (In Persian).
[9]     Oosterom, W.J., “Flying V Family Design”, MSc Thesis, Delft University of Technology, 2020.
[10]  Stenfelt, G., and Ringertz, U., “Lateral Stability and Control of a Tailless Aircraft Configuration”, Journal of Fluid Aircraft, Vol. 46, No. 6, pp. 2161–2164, 2009.
[11]  Tomac, M., and Stenfelt, G., “Predictions of Stability and Control for a Flying Wing”, Aerospace Science and Technology, Vol. 39, pp. 179–186, 2014.
[12]  Stenfelt, G., and Ringertz, U., “Yaw Control of a Tailless Aircraft Configuration”, Journal of Aircraft, Vol. 47, No. 5, pp. 1807–1811, 2010.
[13]  Karimi Kelayeh, R., and Djavarshkian, M.H., “Aerodynamic Investigation of Twist Angle Variation Based on Wing Smarting for a Flying Wing”, Chinese Journal of Aeronautics, 2020.
[14]  Karimi Kelayeh, R., and Djavarshkian, M.H., “Evaluation of Aerodynamic Performance of the Geometrical Twist by Variation of the Reynolds Number in a Flying Wing”, Scientific-Research Journal of Aviation Engineering, Vol. 22, No. 1, Spring-Summer 2020 (In Persian).
[15]  Madani, A., Djavarshkian, M.H., and Karimi Kalayeh, R., “Optimization of Split Drag Rudder Mechanism at Different Angles of Attack in a Flying Wing Airplane”, Fluid Mechanics & Aerodynamics Journal, Vol. 11, No. 1, pp. 1–16, 2022 (In Persian).https://dor.isc.ac/dor/20.1001.1.23223278.1401.11.1.1.3
[16]  Madani, A., Djavarshkian, M.H., “Reducing the Rolling Moment Coefficient in the Use of Split Drag Rudder System Using Wing Fences”, Aerospace Knowledge and Technology Journal, Vol. 12, No. 2, pp. 61-77, 2024 (In Persian).
[17]  Fish, F.E., and Battle, J.M., “Hydrodynamic Design of the Humpback Whale Flipper”, Journal of Morphology, Vol. 225, pp. 51–60, 1995.
[18]  Miklosovic, D.S., Murray, M.M., Howle, L.E., et al., “Leading-Edge Tubercles Delay Stall on Humpback Whale (Megaptera novaeangliae) Flippers”, Physics of Fluids, Vol. 16, No. 5, 2004
[19]  Miklosovic, D.S., Murray, M.M., Howle, L.E., “Experimental Evaluation of Sinusoidal Leading Edges”, Journal of Aircraft, Vol. 44, No. 4, July–August 2007
[20]  Chen, H., Pan, C., and Wang, J.J., “Effects of Sinusoidal Leading Edge on Delta Wing Performance and Mechanism”, Science China Technological Sciences, Vol. 56, pp. 772–779, 2013
[21]  Tomac, M., and Stenfelt, G., “Predictions of Stability and Control for a Flying Wing”, Aerospace Science and Technology, Vol. 39, pp. 179–186, 2014.
[22]  Jansson, N., and Stenfelt, G., “Steady and Unsteady Pressure Measurements on a Swept-Wing Aircraft”, The Aeronautical Journal, Vol. 118, pp. 109–122, 2014.
[23]  Kelayeh, R. K., and  Djavareshkian, M. H. “Aerodynamic investigation of twist angle variation based on wing smarting for a flying wing”, Chinese J Aeronaut. Vol. 34, pp. 201–216, 2021.
[24]  Djavarshkian, M.H., and Karimi Kelayeh, R., “Evaluation of Aerodynamic Performance of Geometric Torsion by Changing Reynolds Number in a Flying Aircraft Model”, Journal of Aviation Engineering, Vol. 22, No. 1, pp. 30–45, 2021 (In Persian).
[25]  ANSYS, Inc I., “Ansys fluent Theory Guide R17”, Southpointe, Pennsylvania, United States, 2016.
Fluid Mechanics & Aerodynamics
Volume 14, Issue 1 - Serial Number 35
Spring and summer
September 2025
Pages 1-19

  • Receive Date 11 April 2025
  • Revise Date 18 July 2025
  • Accept Date 20 August 2025
  • Publish Date 23 August 2025