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Steady and transient response of a laminar separation bubble to controlled disturbances

Published online by Cambridge University Press:  26 January 2017

Serhiy Yarusevych  and
Marios Kotsonis
Serhiy Yarusevych*
Affiliation:
Department of Mechanical and Mechantronics Engineering, University of Waterloo, 200 University Ave. W, Waterloo, Ontario, N2L 3G1, Canada
Marios Kotsonis
Affiliation:
Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, Delft, 2629HS, The Netherlands
*
†Email address for correspondence: syarus@uwaterloo.ca
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Abstract

The steady and transient response of a laminar separation bubble to flow disturbances is examined experimentally. Wind tunnel experiments are performed on a NACA 0012 aerofoil at a chord Reynolds number of 130 000 and angle of attack of $2^{\circ }$. Under the investigated conditions, a laminar separation bubble forms on the suction side of the aerofoil in the unperturbed flow. Periodic disturbances are introduced into the boundary layer just upstream of separation by means of a surface-mounted dielectric barrier discharge plasma actuator. Two-component, time-resolved particle image velocimetry measurements are performed to characterise both quasi-steady and transient response of the flow to periodic disturbances. The results show that the dynamics of the laminar separation bubble is dominated by the periodic shedding of shear layer vortices, forming upstream of the mean reattachment location due to the amplification of unstable flow disturbances. Introducing the controlled perturbations leads to significant changes in separation bubble topology and the characteristics of the dominant coherent structures, with the effect dependent on both amplitude and frequency of disturbances. Linear stability analysis demonstrates that the induced changes to the mean bubble topology affect the stability characteristics, reducing the maximum growth rate and the frequency of the most amplified disturbances by 35 % and 20 %, respectively, when the bubble length is reduced by up to 40 %. The observed changes in stability characteristics are shown to correlate with the attendant variations in the shape factor. The transient response of the bubble is associated with significant changes in the separation bubble dynamics, with significant differences observed between the relative duration (${\approx}45\,\%$) of the transients flow response associated with the introduction and removal of the controlled disturbances. A detailed analysis of the results offers new insight into the response of laminar separation bubbles to changes in the disturbance environment.

JFM classification

Boundary Layers: Boundary layer separation Instability: Transition to turbulence Vortex Flows: Vortex shedding
Type
Papers
Information
Journal of Fluid Mechanics , Volume 813 , 25 February 2017 , pp. 955 - 990
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Copyright
© 2017 Cambridge University Press 

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References

Alam, M. & Sandham, N. D. 2000 Direct numerical simulation of short laminar separation bubbles with turbulent reattachment. J. Fluid Mech. 410, 223–250.Google Scholar
Amitay, M. & Glezer, A. 2002 Controlled transients of flow reattachment over stalled airfoils. Intl J. Heat Fluid Flow 23 (5), 690–699.Google Scholar
Asada, K., Nonomura, T., Aono, H., Sato, M., Okada, K. & Fujii, K. 2015 Les of transient flows controlled by dbd plasma actuator over a stalled airfoil. Intl J. Comput. Fluid Dyn. 29 (3–5), 215–229.Google Scholar
Ashpis, D. E. & Reshotko, E. 1990 The vibrating ribbon problem revisited. J. Fluid Mech. 213, 531–547.Google Scholar
Benard, N., Cattafesta, L. N. III, Moreau, E., Griffin, J. & Bonnet, J. P. 2011 On the benefits of hysteresis effects for closed-loop separation control using plasma actuation. Phys. Fluids 23 (8), 083601.Google Scholar
Benard, N. & Moreau, E. 2014 Electrical and mechanical characteristics of surface AC dielectric barrier discharge plasma actuators applied to airflow control. Exp. Fluids 55 (11), 1–43.Google Scholar
Boiko, A. V., Grek, G. R., Dovgal, A. V. & Kozlov, V. V. 2002 The Origin of Turbulence in Near-Wall Flows. Springer.Google Scholar
Boutilier, M. S. H. & Yarusevych, S. 2012 Separated shear layer transition over an airfoil at a low Reynolds number. Phys. Fluids 24 (8), 084105.Google Scholar
Boutilier, M. S. H. & Yarusevych, S. 2013 Sensitivity of linear stability analysis of measured separated shear layers. Eur. J. Mech. (B/Fluids) 37, 129–142.Google Scholar
Bridges, J. & Morris, P. J. 1984 Differential eigenvalue problems in which the parameter appears nonlinearly. J. Comput. Phys. 437, 222–224.Google Scholar
Brinkerhoff, J. R. & Yaras, M. I. 2011 Interaction of viscous and inviscid instability modes in separation bubble transition. Phys. Fluids 23 (12), 124102.CrossRefGoogle Scholar
Brooks, T. F., Marcolini, M. A. & Pope, D. S. 1986 Airfoil trailing-edge flow measurements. AIAA J. 24 (8), 1245–1251.CrossRefGoogle Scholar
Burgmann, S. & Schröder, W. 2008 Investigation of the vortex induced unsteadiness of a separation bubble via time-resolved and scanning PIV measurements. Exp. Fluids 45 (4), 675–691.Google Scholar
Carmichael, B. H.1981 Low Reynolds number airfoil survey. NASA CR 165803.Google Scholar
Cattafesta, L. N. III & Sheplak, M. 2011 Actuators for active flow control. Annu. Rev. Fluid Mech. 43, 247–272.Google Scholar
Corke, T. C., Bowles, P. O., He, C. & Matlis, E. H. 2011 Sensing and control of flow separation using plasma actuators. Phil. Trans. R. Soc. Lond. A 369 (1940), 1459–1475.Google ScholarPubMed
Corke, T. C., Enloe, C. L. & Wilkinson, S. P. 2010 Dielectric barrier discharge plasma actuators for flow control. Annu. Rev. Fluid Mech. 42, 505–529.CrossRefGoogle Scholar
Darabi, A. & Wygnanski, I. 2004 Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process. J. Fluid Mech. 510, 105–129.Google Scholar
Debien, A., Aubrun, S., Mazellier, N. & Kourta, A. 2015 Active separation control process over a sharp edge ramp. In Ninth International Symposium on Turbulence and Shear Flow Phenomena, Melbourne, Australia.Google Scholar
Desquesnes, G., Terracol, M. & Sagaut, P. 2007 Numerical investigation of the tone noise mechanism over laminar airfoils. J. Fluid Mech. 591, 155–182.Google Scholar
Diwan, S. S. & Ramesh, O. N. 2009 On the origin of the inflectional instability of a laminar separation bubble. J. Fluid Mech. 629, 263–298.Google Scholar
Dovgal, A. V., Kozlov, V. V. & Michalke, A. 1994 Laminar boundary layer separation: instability and associated phenomena. Prog. Aerosp. Sci. 30, 61–94.Google Scholar
Gaster, M.1967 The structure and behaviour of Laminar separation bubbles. Rep. Mem. No. 3595. Aeronautical Research Council.Google Scholar
Glezer, A. & Amitay, M. 2002 Synthetic jets. Annu. Rev. Fluid Mech. 34 (1), 503–529.Google Scholar
Goodfellow, S. D., Yarusevych, S. & Sullivan, P. E. 2012 Momentum coefficient as a parameter for aerodynamic flow control with synthetic jets. AIAA J. 51 (3), 623–631.Google Scholar
Häggmark, C. P., Hildings, C. & Henningson, D. S. 2001 A numerical and experimental study of a transitional separation bubble. Aerosp. Sci. Technol. 5 (5), 317–328.Google Scholar
Hain, R., Kähler, C. J. & Radespiel, R. 2009 Dynamics of laminar separation bubbles at low-Reynolds-number aerofoils. J. Fluid Mech. 630, 129–153.Google Scholar
Jeong, J. & Hussain, F. 1995 On the identification of a vortex. J. Fluid Mech. 285, 69–94.Google Scholar
Jones, L. E., Sandberg, R. D. & Sandham, N. D. 2008 Direct numerical simulations of forced and unforced separation bubbles on an airfoil at incidence. J. Fluid Mech. 602, 175–207.CrossRefGoogle Scholar
Kotapati, R. B., Mittal, R., Marxen, O., Ham, F., You, D. & Cattafesta, L. N. 2010 Nonlinear dynamics and synthetic-jet-based control of a canonical separated flow. J. Fluid Mech. 654, 65–97.Google Scholar
Kotsonis, M. 2015 Diagnostics for characterisation of plasma actuators. Meas. Sci. Technol. 26 (9), 092001.Google Scholar
Kotsonis, M. & Ghaemi, S. 2011 Forcing mechanisms of dielectric barrier discharge plasma actuators at carrier frequency of 625 Hz. J. Appl. Phys. 110 (11), 113301.Google Scholar
Kotsonis, M., Pul, R. & Veldhuis, L. 2014 Influence of circulation on a rounded-trailing-edge airfoil using plasma actuators. Exp. Fluids 55 (7), 1–14.Google Scholar
Lang, M., Rist, U. & Wagner, S. 2004 Investigations on controlled transition development in a laminar separation bubble by means of LDA and PIV. Exp. Fluids 36 (1), 43–52.Google Scholar
LeBlanc, P., Blackwelder, R. & Liebeck, R. 1989 A compariosn between boundary layer measurements in a laminar separation bubble flow and linear stability theory calculations. In Low Reynolds Number Aerodynamics Conference, Notre Dame, Springer.Google Scholar
Lengani, D., Simoni, D., Ubaldi, M. & Zunino, P. 2014 Pod analysis of the unsteady behavior of a laminar separation bubble. Exp. Therm. Fluid Sci. 58, 70–79.Google Scholar
Lin, J. C. M. & Pauley, L. L. 1996 Low-Reynolds-number separation on an airfoil. AIAA J. 34 (8), 1570–1577.Google Scholar
Lissaman, P. B. S. 1983 Low-Reynolds-number airfoils. Annu. Rev. Fluid Mech. 15 (1), 223–239.Google Scholar
Marxen, O. & Henningson, D. S. 2011 The effect of small-amplitude convective disturbances on the size and bursting of a laminar separation bubble. J. Fluid Mech. 671, 1–33.Google Scholar
Marxen, O., Kotapati, R. B., Mittal, R. & Zaki, T. 2015 Stability analysis of separated flows subject to control by zero-net-mass-flux jet. Phys. Fluids 27 (2), 024107.Google Scholar
Marxen, O., Lang, M. & Rist, U. 2012 Discrete linear local eigenmodes in a separating laminar boundary layer. J. Fluid Mech. 711, 1–26.CrossRefGoogle Scholar
Marxen, O., Lang, M. & Rist, U. 2013 Vortex formation and vortex breakup in a laminar separation bubble. J. Fluid Mech. 728, 58–90.Google Scholar
Marxen, O. & Rist, U. 2010 Mean flow deformation in a laminar separation bubble: separation and stability characteristics. J. Fluid Mech. 660, 37–54.Google Scholar
Mathis, R., Lebedev, A., Collin, E., Delville, J. & Bonnet, J. P. 2009 Experimental study of transient forced turbulent separation and reattachment on a bevelled trailing edge. Exp. Fluids 46 (1), 131–146.CrossRefGoogle Scholar
Michelis, T. & Kotsonis, M. 2015 Flow control on a transport truck side mirror using plasma actuators. Trans. ASME J. Fluids Engng 137 (11), 111103.Google Scholar
Mueller, T. J. & DeLaurier, J. D. 2003 Aerodynamics of small vehicles. Annu. Rev. Fluid Mech. 35 (1), 89–111.CrossRefGoogle Scholar
Ol, M. V., Mcauliffe, B. R., Hanff, E. S., Scholz, U. & Kähler, C. 2005 Comparison of laminar separation bubble measurements on a low Reynolds number airfoil in three facilities. In 35th AIAA Fluid Dynamics Conference and Exhibit, Toronto.Google Scholar
Olson, D. A., Katz, A. W., Naguib, A. M., Koochesfahani, M. M., Rizzetta, D. P. & Visbal, M. R. 2013 On the challenges in experimental characterization of flow separation over airfoils at low Reynolds number. Exp. Fluids 54 (2), 1–11.Google Scholar
Pröbsting, S. & Yarusevych, S. 2015 Laminar separation bubble development on an airfoil emitting tonal noise. J. Fluid Mech. 780, 167–191.CrossRefGoogle Scholar
Rist, U. & Maucher, U. 2002 Investigations of time-growing instabilities in laminar separation bubbles. Eur. J. Mech. (B/Fluids) 21 (5), 495–509.Google Scholar
Rist, U., Maucher, U. & Wagner, S. 1996 Direct numerical simulation of some fundamental problems related to transition in laminar separation bubbles. In Comput. Meth. Appl. Sci., pp. 319–325. John Wiley & Sons.Google Scholar
Rizzetta, D. P. & Visbal, M. R. 2011 Numerical investigation of plasma-based control for low-Reynolds-number airfoil flows. AIAA J. 49 (2), 411–425.Google Scholar
Robinet, J. C. 2013 Instabilities in laminar separation bubbles. J. Fluid Mech. 732, 1–4.CrossRefGoogle Scholar
Rodríguez, D., Gennaro, E. M. & Juniper, M. P. 2013 The two classes of primary modal instability in laminar separation bubbles. J. Fluid Mech. 734, R4.Google Scholar
Schmid, P. J. & Henningson, D. S. 2001 Stability and Transition in Shear Flows. vol. 142. Springer.Google Scholar
Sciacchitano, A., Neal, D. R., Smith, B. L., Warner, S. O., Vlachos, P. P., Wieneke, B. & Scarano, F. 2015 Collaborative framework for piv uncertainty quantification: comparative assessment of methods. Meas. Sci. Technol. 26 (7), 1–16.CrossRefGoogle Scholar
Serna, J. & Lázaro, B. J. 2015 Experiments on natural transition in separation bubbles. Procedia IUTAM 14, 496–502.CrossRefGoogle Scholar
Siauw, W. L., Bonnet, J. P., Tensi, J., Cordier, L., Noack, B. R. & Cattafesta, L. 2010 Transient dynamics of the flow around a Naca 0015 airfoil using fluidic vortex generators. Intl J. Heat Fluid Flow 31 (3), 450–459.CrossRefGoogle Scholar
Tani, I. 1964 Low-speed flows involving bubble separations. Prog. Aerosp. Sci. 5, 70–103.CrossRefGoogle Scholar
Theofilis, V., Hein, S. & Dallmann, U. 2000 On the origins of unsteadiness and three-dimensionality in a laminar separation bubble. Phil. Trans. R. Soc. Lond. A 358 (1777), 3229–3246.Google Scholar
Watmuff, J. H. 1999 Evolution of a wave packet into vortex loops in a laminar separation bubble. J. Fluid Mech. 397, 119–169.Google Scholar
Yarusevych, S., Kawall, J. G. & Sullivan, P. E. 2006a Airfoil performance at low Reynolds numbers in the presence of periodic disturbances. Trans. ASME J. Fluids Engng 128 (3), 587–595.Google Scholar
Yarusevych, S., Sullivan, P. E. & Kawall, J. G. 2006b Coherent structures in an airfoil boundary layer and wake at low Reynolds numbers. Phys. Fluids 18 (4), 044101.Google Scholar
Yarusevych, S., Sullivan, P. E. & Kawall, J. G. 2007 Effect of acoustic excitation amplitude on airfoil boundary layer and wake development. AIAA J. 45 (4), 760–771.Google Scholar
Yarusevych, S., Sullivan, P. E. & Kawall, J. G. 2009 On vortex shedding from an airfoil in low-Reynolds-number flows. J. Fluid Mech. 632, 245–271.Google Scholar
Zaman, K. B. M. Q. 1992 Effect of acoustic excitation on stalled flows over an airfoil. AIAA J. 30 (6), 1492–1499.Google Scholar