Hostname: page-component-f554764f5-rvxtl Total loading time: 0 Render date: 2025-04-09T19:12:02.195Z Has data issue: false hasContentIssue false
  • English
  • Français

Dynamics of laminar separation bubbles at low-Reynolds-number aerofoils

Published online by Cambridge University Press:  10 July 2009

R. HAIN ,
C. J. KÄHLER  and
R. RADESPIEL
R. HAIN
Affiliation:
Institute of Fluid Mechanics, Technische Universität Braunschweig, 38106 Braunschweig, Germany
C. J. KÄHLER*
Affiliation:
Institute of Fluid Mechanics, Technische Universität Braunschweig, 38106 Braunschweig, Germany
R. RADESPIEL
Affiliation:
Institute of Fluid Mechanics, Technische Universität Braunschweig, 38106 Braunschweig, Germany
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The laminar separation bubble on an SD7003 aerofoil at a Reynolds number Re = 66000 was investigated to determine the dominant frequencies of the transition process and the flapping of the bubble. The measurements were performed with a high-resolution time-resolved particle image velocimetry (TR-PIV) system. Contrary to typical measurements performed through conventional PIV, the different modes can be identified by applying TR-PIV. The interaction between the shed vortices is analysed, and their significance for the production of turbulence is presented. In the shear layer above the bubble the generation and amplification of vortices due to Kelvin–Helmholtz instabilities is observed. It is found that these instabilities have a weak coherence in the spanwise direction. In a later stage of transition these vortices lead to a three-dimensional breakdown to turbulence.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 630 , 10 July 2009 , pp. 129 - 153
Copyright
Copyright © Cambridge University Press 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

REFERENCES

Alam, M. & Sandham, N. D. 2000 Direct numerical simulation of ‘short’ laminar separation bubbles with turbulent reattachment. J. Fluid Mech. 410, 1–28.CrossRefGoogle Scholar
Arnal, D. 1994 Boundary layer transition: predictions based on linear theory. AGARD R-793, 2.1–2.63.Google Scholar
Burgmann, S., Brücker, C. & Schröder, W. 2006 Scanning PIV measurements of a laminar separation bubble. Exp. Fluids 41, 319–326.CrossRefGoogle Scholar
Drela, M. 2007 XFoil. http://web.mit.edu/drela/Public/web/xfoil/.Google Scholar
Hain, R. & Kähler, C. J. 2005 Advanced evaluation of time-resolved PIV image sequences. In Sixth Intl Symp. on Particle Image Velocimetry, Pasadena, California.Google Scholar
Hain, R. 2008 Untersuchungen zur Dynamik Laminarer Ablöseblasen mit der zeitauflösenolen Particle Image Velocimetry. PhD dissertation, Tu Braunschweig. Shaker Verlag, Aachen, Germany.Google Scholar
Hain, R. & Kähler, C. J. 2007 Fundamentals of multiframe particle image velocimetry (PIV). Exp. Fluids 42, 575–587.CrossRefGoogle Scholar
Hain, R., Kähler, C. J. & Tropea, C. 2007 Comparison of CCD, CMOS and intensified cameras. Exp. Fluids 42, 403–411.CrossRefGoogle Scholar
Horton, H. 1968 Laminar separation bubbles in two and three dimensional incompressible flow. PhD thesis, Department of Aeronautical Engineering, Queen Mary College, University of London.Google Scholar
Jeong, J. & Hussain, F. 1995 On the identification of a vortex. J. Fluid Mech. 285, 69–94.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
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, 43–52.Google Scholar
Lou, W. & Hourmouziadis, J. 2000 Separation bubbles under steady and periodic–unsteady main flow conditions. J. Turbomachin. 122, 634–643.CrossRefGoogle Scholar
Mack, L. M. 1977 Transition prediction and linear stability theory. AGARD CP 224, 1.1–1.22.Google Scholar
Marxen, O., Rist, U. & Wagner, S. 2004 The effect of spanwise-modulated disturbances on transition in a 2-D separated boundary layer. AIAA 42, 937–944.CrossRefGoogle Scholar
Murray, M. M. & Howle, L. E. 2003 Spring stiffness influence on an oscillating propulsor. J. Fluids Struct. 17, 915–926.CrossRefGoogle Scholar
Ol, M. V., Hanff, E., McAuliffe, B., 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 Conf. and Exhibit, Toronto, ON, Canada. Paper 2005-5149. AIAA.Google Scholar
Owen, P. R. & Klanfer, L. 1953 On the laminar boundary layer separation from the leading edge of a thin aerofoil. In ARC Conf. Proc., p. 220.Google Scholar
Piirto, M., Saarenrinne, P., Eloranta, H. & Karvinen, R. 2003 Measuring turbulence energy with PIV in a backward-facing step flow. Exp. Fluids 35, 219–236.CrossRefGoogle Scholar
Seitz, A. & Horstmann, K. H. 2006 In-flight investigations of tollmien-schlichting waves. In IUTAM Symposium on One Hundred Years of Boundary Layer Research. Proceedings of the IUTAM Symposium Held at DLR-Göttingen, Germany, August 12–14 2004, pp. 115–124. Springer.Google Scholar
Selig, M. S., Donovan, J. F. & Fraser, D. B. 1989 Airfoils at Low Speeds. SoarTech.Google Scholar
Spalart, P. R. & Strelets, M. K. H. 2000 Mechanisms of transition and heat transfer in a separation bubble. J. Fluid Mech. 403, 329–349.CrossRefGoogle Scholar
Vollmers, H. 2001 Detection of vortices and quantitative evaluation of their main parameters from experimental velocity data. Meas. Sci. Technol. 12, 1199–1207.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
Wilson, P. G. & Pauley, L. L. 1998 Two- and three-dimensional large-eddy simulations of a transitional separation bubble. Phys. Fluids 10, 2932–2940.CrossRefGoogle Scholar
Windte, J., Scholz, U. & Radespiel, R. 2006 Validation of the RANS-simulation of laminar separation bubbles on airfoils. Aerosp. Sci. Technol. 10, 484–494.CrossRefGoogle Scholar
Wissink, J. & Rodi, W. 2004 DNS of a Laminar Separation Bubble Affected by Free-Stream Disturbances. Springer/Kluwer Academic.CrossRefGoogle Scholar