Accounting for dynamic conditions of aerofoil flow-around while solving the problem of a helicopter main rotor trimming angles determining

Aerodynamics and heat-exchange processes in flying vehicles


Garipova L. I.*, Batrakov A. S.**, Kusyumov A. N.***

Kazan National Research Technical University named after A.N. Tupolev, 10, Karl Marks str., Kazan, 420111, Russia



The main rotor trimming is one of the important tasks of helicopter aerodynamics. The aim of trimming consists in determining the values of balancing angles (total and cyclic pitch angles) of the main rotor, which allows minimize longitudinal and lateral moments, as well as vibration load. A simple approach to the main rotor's balancing angles determination is based on the Blade Element Momentum Theory (BEMT), based on steady-state aerofoil aerodynamics. However, while straight and level flight the helicopter's blade sections motion bears a complex oscillated character. For this reason, aerofoil performances can differ significantly from its steady-state equivalents.

The aim of this research is numerical simulation of the oscillating NACA 23012 aerofoil flow-around to study the effect of dynamic flow conditions corresponding to a forward flight mode on the values of the main rotor trimming (total and cyclic pitch) angles. Numerical simulation was performed using HMB code (Liverpool and Glasgow universities) based on the Unsteady Reynolds averaged Navier–Stokes equations (URANS) with k‒ω SST turbulence model.

The results of study revealed that the dynamic condition leads to significant changes of the aerofoil aerodynamic characteristics and the main rotor trimming angles compared to the steady state formulation. Based on these results a correction can be employed to improve the simple BEMT approach accuracy.


computational aerodynamics (CAD), URANS modeling, rotor trimming angles


  1. Ignatkin Yu.M., Makeev P.V., Shomov A.I. Trudy MAI, 2016, no 87, available at:

  2. Ignatkin Yu.M., Makeev P.V., Shomov A.I. Trudy MAI, 2013, no. 69, available at:

  3. Steijl R., Barakos G., Badcock K. A framework for CFD analysis of helicopter rotors in hover and forward flight, International Journal for Numerical Methods in Fluids, 2006, vol. 51, pp. 819-828.

  4. Ilkko J., Hoffren J., Siikonen T. Simulation of a helicopter rotor flow, Rakenteiden Mekaniikka. (Journal of Structural Mechanics), 2011, vol. 44, no. 3, pp.186-205.

  5. Batrakov A.S., Kusyumov A.N., Garipova L.I., Mikhailov S.A., Barakos G.N. The flow around helicopter main rotor in forward flight, The 4th International Conference on Advances in Mechanics Engineering (ICAME 2015), Madrid, Spain, 2015, pp. 1-4.

  6. Bramwell A.R.S., Done G., Balmford D. Bramwell’s helicopter dynamics, 2nd edition, Published by Butterworth-Heinemann, 2001, 372 p.

  7. Barakos G.N., Drikakis D. Computational study of unsteady turbulent flows around oscillating and ramping aerofoils, International Journal for Numerical Methods in Fluids, 2003, no. 42, pp. 163-186.

  8. Dumlupinar E., Murthy V.R. Investigation of dynamic stall of airfoils and wings by CFD, 29th AIAA Applied Aerodynamics Conference, 27-30 June 2011, Honolulu, Hawaii, pp. 1-29.

  9. Batrakov A.S., Kusyumov A.N. Simpozium Batrakov A.S., Kusyumov A.N. Simpozium “Samoletostroenie Rossii. Problemy i perspektivy”. Sbornik trudov, Samara, 2-5 iyulya 2012, pp. 66-68.

  10. Nik Mohd N.A.R., Barakos G.N. Computational aerodynamics of hovering helicopter rotors, Jurnal Mekanikal, June 2012, no. 34, pp. 16-46.

  11. Batrakov A.S., Garipova L.I., Kusyumov A.N., Barakos G.N. Application of Computational Fluid Dynamics in the problems of determining the aerodynamic characteristics of the helicopter, DOAJ — Lund University: Koncept: Scientific and Methodological e-magazine, 2014, Lund, no. 4 (Collec0ted works, Best Article), vol. 1, pp. 391-395, available at:

  12. Menter F.R. Two-equation eddy-viscosity turbulence models for engineering applications, AIAA Journal, 1994, vol. 32, no. 8, pp. 1598-1605.

  13. Garbaruk A.V., Strelets M.Kh., Shur M.L. Modelirovanie turbulentnosti v raschetakh slozhnykh techenii (Simulation of turbulence in complex flows computation), Saint-Petersburg, Izd-vo Politekhnicheskogo universiteta, 2012, 88 p.

  14. Abbot I., von Doenhoff A.E. Theory of wing section. Including a Summary of Airfoil, Data Dover Publications: INC. New York, 1959, 705 p.

  15. Garipova L.I. Kusyumov A.N. XVI Vserossiiskii seminar po upravleniyu dvizheniem i navigatsii letatel’nykh apparatov. Sbornik trudov. Samara, izd-vo SNTs RAN, 2013. Ch. I. C. 178 −181.

  16. Krasnov N.F. Ajerodinamika. Osnovy teorii. Ajerodinamika profilja i kryla (Aerodynamics. Fundamentals of the theory. Aerodynamics of the profile and the wing.), Мoscow, Vysshaya shkola, 1976, 384 p.

Download — informational site MAI

Copyright © 2000-2024 by MAI