Estimation of Aerodynamic Coefficients in a Small Subsonic Wind Tunnel

  • Karolina Krajček Nikolić University of Zagreb
  • Anita Domitrović University of Zagreb
  • Slobodan Janković University of Zagreb
Keywords: wind tunnel corrections, Reynolds number scaling, model support correction


To apply the experimental data measured in a wind tunnel for a scaled aircraft to a free-flying model, conditions of dynamical similarity must be met or scaling procedures introduced. The scaling methods should correct the wind tunnel data regarding model support, wall interference, and lower Reynolds number. To include the necessary corrections, the current scaling techniques use computational fluid dynamics (CFD) in combination with measurements in cryogenic wind tunnels. There are a few methods that enable preliminary calculations of typical corrections considering specific measurement conditions and volume limitation of test section. The purpose of this paper is to present one possible approach to estimating corrections due to sting interference and difference in Reynolds number between the real airplane in cruise regime and its 1:100 model in the small wind tunnel AT-1. The analysis gives results for correction of axial and normal force coefficients. The results of this analysis indicate that the Reynolds number effects and the problem of installation of internal force balance are quite large. Therefore, the wind tunnel AT-1 has limited  usage for aerodynamic coefficient determination of transport airplanes, like Dash 8 Q400 analyzed in this paper.


[1] Pettersson K, Rizzi A. Aerodynamic Scaling to Free Flight Conditions: Past and Present. Progress in Aerospace Sciences. 2008;44(4): 295-313.
[2] Barlow JB, Rae WH, Pope A. Low-Speed Wind Tunnel Testing. New York: John Wiley &Sons; 1999.
[3] Horsten BJC. Low-Speed Model Support Interference - Elements of an Expert System. PhD thesis. Delft: Delft University of Technology; 2009.
[4] Bushnell DM. Scaling: Wind Tunnel to Flight. Annual Review of Fluid Mechanics. 2006;38: 111-128.
[5] Traub LW. Drag Extrapolation to Higher Reynolds Number. Journal of Aircraft. 2009;46(4): 1458-1461.
[6] Mirzaei M, Karimi MH, Vaziri MA. An Investigation of a Tactical Cargo Aircraft Aft Body Drag Reduction Based on CFD Analysis and Wind Tunnel Tests. Aerospace Science and Technology. 2012;23(1): 263-269.
[7] Pettersson K, Rizzi A. Reynolds Number Effects Identified with CFD Methods Compared to Semi-Empirical Methods. In: Proceedings of the 25th International Congress of the Aeronautical Sciences (ICAS 2006), 3-8 September 2006, Hamburg, Germany. Curran Associates, Inc; 2006. p. 1566-1579.
[8] Maina M, Corby N, Crocker EL, Hammond PJ, Wong PWC. A feasiblity study on designing model support systems for a blended wing body configuration in a transonic wind tunnel. Aeronautical Journal. 2006;110(1103): 53-62.
[9] Rudnik R, Germain E. Reynolds Number Scaling Effects on the European High-Lift Project Configurations. Journal of Aircraft. 2009;46(4): 1140-1151.
[10] Pamadi B. Performance, Stability, Dynamics, and Control of Airplanes. Reston, Virginia: AIAA; 1998.
[11] Janković S. [Aircraft Flight Mechanics]. Zagreb: Faculty of Mechanical Engineering and Naval Architecture; 2002. Croatian
[12] Лебедев AA. Динамика полета: Машиностроение. Москва; 1973.
[13] Janković S. [Aerodynamic Coefficients Estimation for Dash 8 Q400 in Flight]. Zagreb: Faculty of Transport and Traffic Sciences; 2017. Croatian
How to Cite
Krajček Nikolić K, Domitrović A, Janković S. Estimation of Aerodynamic Coefficients in a Small Subsonic Wind Tunnel. Promet - Traffic & Transportation [Internet]. 10Sep.2018 [cited 17Oct.2018];30(4):457-63. Available from: