Summary
In this study exemplary results on the influence of two fundamental unsteady parameters, the reduced frequency k and the non-dimensional pitching rate α+, on the transition from a steady to an unsteady flow field around the reference airfoil BAC3–11/RES/30/21 are presented using experimental and numerical techniques. The tools used are described and their results verified with each other. On the experimental side, water tunnel experiments are conducted using particle-imagevelocimetry (PIV) and strain-gauge-balance (SGB) measurement techniques. The experimental results are enhanced by two-dimensional laminar unsteady numerical Navier-Stokes simulations of the experiments with a state of the art code from the Featflow package. The numerical simulations are found to agree well with experimental results, despite three-dimensional effects and a relatively high Reynolds number of Re c = 16000. An influence of the reduced frequency on the lift coefficient at a local non-dimensional pitching rate value of α+= 0 for the relevant range is not detected, while for the drag and the pitching moment a decrease and an increase respectively is observed. Nevertheless a phase difference for the lift with increasing reduced frequency was calculated, which appears at least above k = 0.14 and indicates unsteady effects. The same was observed for the pitching moment. The effects of the airfoil camber are clearly seen during the phase of negative angle of attack, inducing leading and trailing edge separation. The flow separation regions are discussed and the formation of a triple vortex system at the trailing edge in the pitching up motion of the airfoil is identified in the experimental and numerical data.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Bublitz, P.: Geschichte der Entwicklung der Aeroelastik in Deutschland von den Anfängen bis 1945. DFVLR-Mitteilung 86–15, (1986).
Bennet, R. M.; Edwards, J. W.: An Overview of Recent Developments in Computational Aeroelasticity. AIAA Paper 1998–2421, 29th Fluid Dynamics Conference, Albuquerque, NM (1998).
Kumar, A.; Hefner, J.: Future Challenges and Opportunities in Aerodynamics. ICAS 2000–0.2.1, ICAS 2000 Congress (2000).
Mccroskey, W. J.: Unsteady Airfoils. Ann. Rev. Fluid Mechanics, Vol. 14, pp. 285–311, (1982).
Akamatsu, T.: Application of shock tube technology to studies of hydrodynamics. Shock Tube and Shock Wave Research (ed. Ahlborn, Hertzberg, Russel), University of Washington Press, Seattle and London, (1978).
Moir, I.R.: Measurements on a Two-Dimensional Airfoil with High-Lift Devices. AGARD-AR-303, A21–A22, (1994).
Wernert, P.; Geissler, W.; Raffel, M.; Kompenhans, J.: Experimental and numerical investigations of dynamic stall on a pitching airfoil. AIAA Journal, Vol. 34, No. 5, p. 982–989, (1996).
Raffel, M.; Willert, C.; Kompenhans, J.: Particle Image Velocimetry: A practical guide. Springer-Verlag, (1998).
Wernert, P.; Favier, D.: Considerations about the phase averaging method with application to ELDV and PIV measurements over pitching airfoils. Experiments in Fluids 27, p. 473–483, Springer-Verlag (1999).
Wernert, P.; Koerber, G.; Wietrich, F. et al.: Demonstration by PIV of the Non-Reproduceability of the Flow Field Around an Airfoil Pitching Under Deep Dynamic Stall Conditions and Consequences Thereof Aerospace Science and Technology, Vol. 2, p. 125–135, (1997).
Adrian, A. J.: Particle-Image Techniques for Experimental Fluid Mechanics. Annual Review of Fluid Mechnics, Vol. 23, p. 261–304(1991).
Weigand, A.: Review of some Novel Measurement Techniques for Fluid Dynamics Studies. DGLR Jahrestagung, Göttingen, Germany (1993).
Willert, C. E.; Gharib, M.: Digital particle image velocimetry. Experiment in Fluids 10, p. 181–193, (1991).
Shand, A. M.: The Investigation, Development and Optimisation of Global Laser Diagnostics for Combustion and Related Flow Applications. PhD Thesis, University of Warwick, (1996).
Turek, S.; Becker, C.: Featflow. Finite element software for the incompressible Navier-Stokes equations. User Manual. Release 1.1. Technical Report, University of Heidelberg, Germany (1998).
Turek, S.: Efficient solvers for incompressible flow problems: An algorithmic approach in view of computational aspects. LNCSE 6, Springer Verlag (1999).
Schäfer, M; Turek, S.: Benchmark Computations of Laminar Flow Around a Cylinder In: Flow Simulation with High-Performance Computers II, Ed. Hirschel, E. H., NNFM Vol. 52, Vieweg Verlag (1996).
Hesse, M.; Britten, G.; Ballmann, J.: A Multi-Block Grid Deformation Algorithm for Aeroelastic Analysis. B. K. Soni, J. Häuser, JE Thomson, P. Eiseman (eds.), Numerical Grid Generation in Computational Field Simulations, Proc. 7th Int. Conf., pp. 161–170 (2000).
Wall, W. A.: Fluid structure interaction with stabilized finite elements. Institute of Structural Mechanics, University of Stuttgart, PhD Thesis (1999).
Ohmi, K.; Coutanceau, M.; Loc, T. et al.: Vortex formation around an oscillating and translating airfoil at large incidences. J. Fluid Mechanics, Vol. 211, pp. 37–60 (1990).
Walker, J. M.; Helin, H. E.; Strickland, J. H.: An Experimental Investigation of an Airfoil Undergoing Large-Amplitude Pitching Motions. AIAA Journal, Vol. 23, No. 8, pp. 1141–1142 (1985).
Theodorsen, T.: General theory of aerodynamic instability and the mechanism of flutter NACA Report 496 (1935).
Bertran, X.: Separation Effects on the Unsteady Aerodynamics of Oscillating Airfoils at Low Speeds. Doctoral Thesis, Stoßwellenlabor, Aachen University (2002).
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2003 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Bertrán, X., Olivier, H., Turek, S. (2003). Analysis of Unsteady Airfoils at Low Speeds. In: Ballmann, J. (eds) Flow Modulation and Fluid—Structure Interaction at Airplane Wings. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, vol 84. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-44866-2_13
Download citation
DOI: https://doi.org/10.1007/978-3-540-44866-2_13
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-53613-7
Online ISBN: 978-3-540-44866-2
eBook Packages: Springer Book Archive