Abstract
Longitudinal flow velocity control was conducted in the Andrew Fejer Unsteady Wind Tunnel to produce velocity spectra that emulate atmospheric turbulence. A louver mechanism placed at the downstream end of the test section determines the resistance to the flow by varying the louver deflection angle, and hence changes the test-section velocity. The test-section flow velocity was decomposed into an adjustable mean flow \(u_0\) and a fluctuation \(u'\), which were respectively controlled by the mean louver deflection angle and the oscillations of the louvers about that mean angle. A linear interpolation of the static map of the test-section flow speed with respect to the louver deflection angle was used as an open-loop controller for the longitudinal flow velocity. A feedback loop that measures the velocity spectrum over a short time interval constructed a closed-loop controller, which controls the mean flow speed as well as the amplitudes over a range of individual frequencies within the fluctuation spectrum. The spectral feedback approach was tested by generating the longitudinal velocity components of von Kármán turbulence spectra and Dryden turbulence spectra. The controller proved to be capable of controlling the gust frequency with a bandwidth of 7 Hz given the current hardware configuration.
Graphic abstract
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Beal TR (1993) Digital simulation of atmospheric turbulence for Dryden and von Kármán models. J Guid Control Dyn 16(1):132–138. https://doi.org/10.2514/3.11437
Carr LW (1988) Progress in analysis and prediction of dynamic stall. J Aircr 25(1):6–17. https://doi.org/10.2514/3.45534
Cherry BE, Constantino MM (2010) The burble effect: superstructure and flight deck effects on carrier air wake. Tech. rep., U. S. Naval Academy Technical Report, dTIC ADA527798
Conlisk AT (1997) Modern helicopter aerodynamics. Annu Rev Fluid Mech 29(1):515–567. https://doi.org/10.1146/annurev.fluid.29.1.515
Diederich FW, Drischler JA (1957) Effect of spanwise variations in gust intensity on the lift due to atmospheric turbulence. Tech. rep., National Advisory Committee for Aeronautics, technical note 3920
Greenblatt D (2016) Unsteady low-speed wind tunnels. AIAA J 54(6):1817–1830. https://doi.org/10.2514/1.J054590
Greenblatt D, Ben-Harav A, Müller-Vahl H (2014) Dynamic stall control on a vertical-axis wind turbine using plasma actuators. AIAA J 52(2):456–462. https://doi.org/10.2514/1.J052776
He X, Williams DR (2020) Unsteady aerodynamic loads on an airfoil at high angle of attack in a randomly surging flow. In: AIAA Scitech 2020 forum, Orlando. https://doi.org/10.2514/6.2020-0557
He X, Asztalos KJ, Williams DR, Buchert K, Henry J (2020) Tailoring wind tunnel gust spectra with feedback control. In: AIAA Scitech 2020 forum, Orlando. https://doi.org/10.2514/6.2020-1557
Hoblit FM (1988) Gust loads on aircraft: concepts and applications. American Institute of Aeronautics and Astronautics, New York
Huyer SA, Simms D, Robinson MC (1996) Unsteady aerodynamics associated with horizontal-axis wind turbines. AIAA J 34(7):1410–1419. https://doi.org/10.2514/3.13247
Kerstens W, Pfeiffer J, Williams DR, King R, Colonius T (2011) Closed-loop control of lift for longitudinal gust suppression at low Reynolds numbers. AIAA J 49(8):1721–1728. https://doi.org/10.2514/1.J050954
Knebel P, Kittel A, Peinke J (2011) Atmospheric wind field conditions generated by active grids. Exp Fluids 51(2):471–481. https://doi.org/10.1007/s00348-011-1056-8
Liepmann HW (1952) On the application of statistical concepts to the buffeting problem. J Aeronaut Sci 19(12):793–800. https://doi.org/10.2514/8.2491
Makita H (1991) Realization of a large-scale turbulence field in a small wind tunnel. Fluid Dyn Res 8(1–4):53–64. https://doi.org/10.1016/0169-5983(91)90030-M
Pfeiffer J (2016) Closed-loop active flow control for road vehicles under unsteady cross-wind conditions. Doctoral dissertation, T U Berlin
Rennie RM, Catron B, Feroz MZ, Williams DR, He X (2019) Dynamic behavior and gust simulation in an unsteady flow wind tunnel. AIAA J 57(4):1423–1433. https://doi.org/10.2514/1.J057186
Roadman JM, Mohseni K (2009) Large scale gust generation for small scale wind tunnel testing of atmospheric turbulence. In: 39th AIAA fluid dynamics conference, San Antonio. https://doi.org/10.2514/6.2009-4166
von Kármán T (1948) Progress in the statistical theory of turbulence. Proc Natl Acad Sci USA 34(11):530
Wei NJ, Kissing J, Wester TTB, Wegt S, Schiffmann K, Jakirlic S, Hlling M, Peinke J, Tropea C (2019) Insights into the periodic gust response of airfoils. J Fluid Mech 876:237–263. https://doi.org/10.1017/jfm.2019.537
Williams DR, Stasse Q, Rennie MR (2019) Lift, drag, and moment response of a UCAS model experiencing longitudinal von Karman gust spectra. In: AIAA Scitech 2019 forum, San Diego. https://doi.org/10.2514/6.2019-1149
Acknowledgements
The support from Air Force Office of Scientific Research Grant FA9550-18-1-0440 with program officer Gregg Abate and Office of Naval Research Grant N00014-19-1-2280 with program officer Brian Holm-Hansen is greatly appreciated. The help on some aspects of hardware and software from Katherine Asztalos and James Henry at IIT is very appreciated. The authors also would like to thank Kevin Buchert from T U Berlin for the modification of the wind tunnel at the preliminary stage.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
He, X., Williams, D.R. Spectral feedback control of turbulent spectra in a wind tunnel. Exp Fluids 61, 175 (2020). https://doi.org/10.1007/s00348-020-03003-8
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00348-020-03003-8