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Control of laminar separation using pulsed vortex generator jets: direct numerical simulations

Published online by Cambridge University Press:  19 April 2011

D. POSTL ,
W. BALZER  and
H. F. FASEL
D. POSTL
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
W. BALZER
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
H. F. FASEL*
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
*
†Email address for correspondence: faselh@email.arizona.edu
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Abstract

Direct numerical simulations (DNS) are employed to investigate laminar boundary layer separation and its control by pulsed vortex generator jets (VGJs), i.e. by injecting fluid into the flow through a spanwise array of small holes. Particular focus is directed towards identifying the relevant physical mechanisms associated with VGJ control of low-Reynolds-number separation, as encountered in low-pressure turbine applications. Pulsed VGJs are shown to be much more effective than steady VGJs when the same momentum coefficient is used for the actuation. From our investigations we have found that the increased control effectiveness of pulsed VGJs can be explained by the fact that linear hydrodynamic instability mechanisms are exploited. When pulsing with frequencies to which the separated shear layer is naturally unstable, instability modes are shown to develop into large-scale, spanwise coherent structures. These structures provide the necessary entrainment of high-momentum fluid to successfully reattach the flow.

JFM classification

Boundary Layers: Boundary layer separation Instability: Instability Flow Control: Flow Control Instability: Transition to turbulence
Type
Papers
Information
Journal of Fluid Mechanics , Volume 676 , 10 June 2011 , pp. 81 - 109
Copyright
Copyright © Cambridge University Press 2011

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References

REFERENCES

Alam, M. & Sandham, N. D. 2000 Direct numerical simulation of ‘short’ laminar separation bubbles with turbulent reattachment. J. Fluid Mech. 403, 223–250.CrossRefGoogle Scholar
Bake, S., Meyer, D. & Rist, U. 2002 Turbulence mechanism in Klebanoff transition: a quantitative comparison of experiment and direct numerical simulation. J. Fluid Mech. 459, 217–243.CrossRefGoogle Scholar
Balzer, W. & Fasel, H. F. 2010 Numerical investigation of the effect of free-stream turbulence on laminar boundary-layer separation. AIAA Paper 2010-4600.CrossRefGoogle Scholar
Berkooz, G., Holmes, P. & Lumley, J. L. 1993 The proper orthogonal decomposition in the analysis of turbulent flows. Annu. Rev. Fluid Mech. 25, 539–575.CrossRefGoogle Scholar
Bloxham, M., Reimann, D., Crapo, K., Pluim, J. & Bons, J. 2007 Synchronizing separation flow control with unsteady wakes in a low-pressure turbine cascade. In IGTI Conference, International Gas Turbine Inst. Paper GT2007-27529, Montreal, Canada.Google Scholar
Bons, J. P., Hansen, L. C., Clark, J. P., Koch, P. J. & Sondergaard, R. 2005 Designing low-pressure turbine blades with integrated flow control. In Proceedings of GT2005, ASME Turbo Expo 2005: Power for Land, Sea, and Air, Reno-Tahoe, NV.Google Scholar
Bons, J. P., Sondergaard, R. & Rivir, R. B. 2001 Turbine separation control using pulsed vortex generator jets. ASME J. Turbomach. 123, 198–206.CrossRefGoogle Scholar
Bons, J. P., Sondergaard, R. & Rivir, R. B. 2002 The fluid dynamics of LPT blade separation control using pulsed jets. ASME J. Turbomach. 124, 77–85.CrossRefGoogle Scholar
Davies, C. & Carpenter, P. W. 2001 A novel velocity–vorticity formulation of the Navier–Stokes equations with applications to boundary layer disturbance evolution. J. Comput. Phys. 172, 119–165.CrossRefGoogle Scholar
Fasel, H. F. 1976 Investigation of the stability of boundary layers by a finite-difference model of the Navier–Stokes equations. J. Fluid Mech. 78 (2), 355–383.CrossRefGoogle Scholar
Ferziger, J. H. 1998 Numerical Methods for Engineering Application, 2nd edn. Wiley.Google Scholar
Gaster, M. 1966 The structure and behaviour of laminar separation bubbles. In AGARD CP 4, pp. 813–854.Google Scholar
Gier, J., Franke, M., Hübner, N. & Schröder, T. 2008 Designing LP turbines for optimized airfoil lift. In Proceedings of GT2008, ASME Turbo Expo 2008: Power for Land, Sea, and Air, Berlin, Germany.Google Scholar
Gross, A., Balzer, W. & Fasel, H. F. 2008 Active separation control for lifting surfaces at low-Reynolds number operating conditions. In HPCMP-UGC '08: Proceedings of the 2008 DoD High Performance Computing Modernization Program Users Group Conference, Washington, DC, USA, pp. 9–17. IEEE Computer Society.CrossRefGoogle Scholar
Gross, A. & Fasel, H. F. 2010 a Active flow control for NACA 6-series airfoil at Re = 64,200. AIAA J. 48 (9), 1889–1902.CrossRefGoogle Scholar
Gross, A. & Fasel, H. F. 2010 b Numerical simulation of low-pressure turbine blade separation control. AIAA J. 48 (8), 1582–1601.Google Scholar
Gruber, K. 1987 Numerische Untersuchungen zum Problem der Grenzschichtablösung. PhD thesis, Universität Stuttgart.Google Scholar
Haidari, A. H. & Smith, C. R. 1994 The generation and regeneration of single hairpin vortices. J. Fluid Mech. 277, 135–161.CrossRefGoogle Scholar
Gad-el Hak, M., Pollard, A. & Bonnet, J.-P. (Ed.) 1998 Flow Control: Fundamentals and Practices. Springer.CrossRefGoogle Scholar
Horton, H. P. 1968 Laminar separation in two and three-dimensional incompressible flow. PhD thesis, University of London.Google Scholar
Huerre, P. & Monkewitz, P. A. 1990 Local and global instabilities in spatially developing flows. Annu. Rev. Fluid Mech. 22, 473–537.CrossRefGoogle Scholar
Jeong, J. & Hussain, F. 1995 On the identification of a vortex. J. Fluid Mech. 285, 69–94.CrossRefGoogle Scholar
Johari, H. & McManus, K. 1997 Visualization of pulsed vortex generator jets for active control of boundary layer separation. AIAA Paper 97-2021.CrossRefGoogle Scholar
Johari, H. & Rixon, G. S. 2003 Effects of pulsing on a vortex generator jet. AIAA J. 41 (12), 2309–2315.CrossRefGoogle 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
Lele, S. K. 1992 Compact finite difference schemes with spectral-like resolution. J. Comput. Phys. 103, 16–42.CrossRefGoogle Scholar
Liu, J. T. C. 1989 Coherent structures in transitional and turbulent free shear flows. Annu. Rev. Fluid Mech. 21, 285–315.CrossRefGoogle Scholar
Marxen, O., Lang, M., Rist, U., Levin, O. & Henningson, D. S. 2009 Mechanisms for spatial steady three-dimensional disturbance growth in a non-parallel and separating boundary layer. J. Fluid Mech. 634, 165–189.CrossRefGoogle Scholar
Marxen, O. & Rist, U. 2010 Mean flow deformation in a laminar separation bubble: separation and stability characteristics. J. Fluid Mech. 660, 37–54.CrossRefGoogle Scholar
Marxen, O., Rist, U. & Wagner, S. 2004 Effect of spanwise-modulated disturbances on transition in a separated boundary layer. AIAA J. 42, 937–944.CrossRefGoogle Scholar
McManus, K., Joshi, P., Legner, H. & Davis, S. 1995 Active control of aerodynamic stall using pulsed jet actuators. AIAA Paper 95-2187.CrossRefGoogle Scholar
McManus, K., Legner, H. & Davis, S. 1994 Pulsed vortex generator jets for active control of separation. AIAA Paper 94-2218.CrossRefGoogle Scholar
Meitz, H. & Fasel, H. F. 2000 A compact-difference scheme for the Navier–Stokes equations in vorticity–velocity formulation. J. Comput. Phys. 157, 371–403.CrossRefGoogle Scholar
Morkovin, M. V. 1969 The many faces of transition. In Viscous Drag Reduction (ed. Wells, C. S.). Plenum.Google Scholar
Orszag, S. A. 1971 Numerical simulation of incompressible flows within simple boundaries: galerkin (spectral) representations. Stud. Appl. Maths 50, 293–327.CrossRefGoogle Scholar
Pauley, L. L. 1994 Response of two-dimensional separation to three-dimensional disturbances. J. Fluids Engng 116, 433–438.CrossRefGoogle Scholar
Pauley, L. L., Moin, P. & Reynolds, W. C. 1990 The structure of two-dimensional separation. J. Fluid Mech. 220, 397–411.CrossRefGoogle Scholar
Postl, D. 2005 Numerical investigation of laminar separation control using vortex generator jets. PhD thesis, University of Arizona.Google Scholar
Postl, D. & Fasel, H. F. 2006 Direct numerical simulation of turbulent flow separation from a wall-mounted hump. AIAA J. 44 (2), 263–272.CrossRefGoogle Scholar
Ripley, M. D. & Pauley, L. L. 1993 The unsteady structure of two–dimensional steady laminar separation. Phys. Fluids 5 (12), 3099–3106.CrossRefGoogle Scholar
Rist, U. & Fasel, H. F. 1995 Direct numerical simulation of controlled transition in a flat-plate boundary layer. J. Fluid Mech. 298, 211–248.CrossRefGoogle Scholar
Rist, U. & Maucher, U. 1994 Direct numerical simulations of 2D and 3D instability waves in a laminar separation bubble. In Proceedings of the AGARD Symposium on Application of Direct and Large Eddy Simulation to Transition and Turbulence, AGARD CP 551, Chania, Crete, Greece.Google Scholar
Schmid, P. J. & Henningson, D. S. 2001 Stability and Transition in Shear Flows. Springer.CrossRefGoogle Scholar
Sondergaard, R., Bons, J. P. & Rivir, R. B. 2002 Control of low-pressure turbine separation using vortex generator jets. J. Propul. Power 18, 889–895.CrossRefGoogle Scholar
Spalart, P. R. & Strelets, M. K. 2000 Mechanisms of transition and heat transfer in a separation bubble. J. Fluid Mech. 403, 329–349.CrossRefGoogle Scholar
Watmuff, J. H. 1999 Evolution of a wave packet into vortex loops in a laminar separation bubble. J. Fluid Mech. 397, 119–169.CrossRefGoogle Scholar

Postl et al. supplementary material

Flow structures associated with pulsed vortex generator jets. Case PV-A. Side view of iso-surfaces of λ2=-5. This animation corresponds to figure 12 in the manuscript.

Download Postl et al. supplementary material(Video)
Video 1.2 MB

Postl et al. supplementary material

Flow structures associated with pulsed vortex generator jets. Case PV-A. Side view of iso-surfaces of λ2=-5. This animation corresponds to figure 12 in the manuscript.

Download Postl et al. supplementary material(Video)
Video 603.2 KB