0
Research Papers: Flows in Complex Systems

Detection of Laminar Flow Separation and Transition on a NACA-0012 Airfoil Using Surface Hot-Films

[+] Author and Article Information
Azemi Benaissa

e-mail: benaissa-a@rmc.ca

Dominique Poirel

Department of Mechanical and Aerospace Engineering,
Royal Military College of Canada,
Kingston, Ontario K7K 7B4, Canada

Contributed by the Fluids Engineering Division of ASME for publication in the Journal of Fluids Engineering. Manuscript received October 2, 2012; final manuscript received April 9, 2013; published online August 6, 2013. Assoc. Editor: Zvi Rusak.

J. Fluids Eng 135(10), 101104 (Aug 06, 2013) (6 pages) Paper No: FE-12-1490; doi: 10.1115/1.4024807 History: Received October 02, 2012; Revised April 09, 2013

A method for mapping the separation and transition of flow over a slowly pitching airfoil with high angular resolution is presented. An array of surface-mounted hot-film sensors is used to record simultaneous corresponding voltages. The method makes use of windowed correlation and spectral signatures of hot-film sensor voltages in synchronization with a servo-motor controlling airfoil pitch angle. Results are given for a NACA-0012 airfoil at three airspeeds at pitch angles of less than 6 deg. The airspeeds correspond to a region of known aeroelastic instability; they are situated between chord Reynolds numbers of 50,000 and 130,000. Tests in static and quasi-static pitch motion schedules were conducted. The quasi-static airfoil was sinusoidally pitching at 0.025 Hz between −6 deg and +6 deg (corresponding to a half-chord based reduced frequency between 0.0011 and 0.0020) and the detected separation and transition agreed very well with the static case. These results constitute a verification of the method used and provide insight into the size and location of the laminar separation bubble at transitional Reynolds numbers.

FIGURES IN THIS ARTICLE
<>
Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Mueller, T., 1985, “Low Reynolds Number Vehicles,” Technical Report No. AGARD-AG 288.
Gad-el Hak, M., 1990, “Control of Low Airfoil Aerodynamics,” AIAA J., 28(9), pp. 1537–1552. [CrossRef]
McMaster, J., and Henderson, M. L., 1980, “Low Speed Single Element Airfoil Synthesis,” Technical Soaring, 6(2), pp. 1–22.
Poirel, D., Harris, Y., and Benaissa, A., 2008, “Self-Sustained Aeroelastic Oscillations of a NACA 0012 Airfoil at Low-to-Moderate Reynolds Numbers,” J. Fluids Struct., 24(5), pp. 700–719. [CrossRef]
Poirel, D., and Yuan, W., 2010, “Aerodynamics of Laminar Separation Flutter at a Transitional Reynolds Number,” J. Fluids Struct., 26, pp. 1174–1194. [CrossRef]
Yuan, W., Poirel, D., Wang, B., and Khalid, M., 2012, “Simulations of Airfoil Limit-Cycle Oscillations at Transitional Reynolds Numbers,” Proceedings of the 50th AIAA Aerospace Sciences Conference, AIAA Paper No. 2012-0041.
Poirel, D., Metivier, V., and Dumas, G., 2011, “Computational Aeroelastic Simulations of Self-Sustained Pitch Oscillations of a NACA0012 at Transitional Reynolds Numbers,” J. Fluids Struct., 27(8), pp. 1262–1277. [CrossRef]
Yen, S., and Fei, Y. F., 2011, “Winglet Dihedral Effect on Flow Behavior and Aerodynamic Performance of NACA0012 Wings,” ASME J. Fluids Eng., 133, pp. 1–9. [CrossRef]
McCroskey, W., 1977, “Some Current Research in Unsteady Fluid Dynamics,” ASME J. Fluids Eng., 99(1), pp. 8–39. [CrossRef]
Rudmin, D., Benaissa, A., and Poirel, D., 2010, “Study of Near Wake Flow Structure of a Pitching Airfoil,” Proceedings of the CSME Forum.
Chew, Y., Khoo, B., Lim, C., and Teo, C., 1998, “Dynamic Response of a Hot-Wire Anemometer. Part II: A Flush-Mounted Hot-Wire and Hot-Film Probes for Wall Shear Stress Measurements,” Meas. Sci. Technol., 9, p. 764. [CrossRef]
Stack, J., Mangalam, S., and Berry, S., 1987, “A Unique Measurement Technique to Study Laminar-Separation Bubble Characteristics on an Airfoil,” Proceedings of the 19th AIAA Fluid Dynamics, Plasma Dynamics, and Lasers Conference, Honolulu, HI, p. 1271.
Lee, T., and Basu, S., 1998, “Measurement of Unsteady Boundary Layer Developed on an Oscillating Airfoil Using Multiple Hot-Film Sensors,” Exp. Fluids, 25(2), pp. 108–117. [CrossRef]
Lee, T., and Gerontakos, P., 2004, “Investigation of Flow Over an Oscillating Airfoil,” J. Fluid Mech., 512(1), pp. 313–341. [CrossRef]
Mangalam, A., and Moes, T., 2004, “Real-Time Unsteady Loads Measurements Using Hot-Film Sensors,” Report No. NASA/TM 2004-212854.
Lorber, P., 1992, “An Oscillating Three-Dimensional Wing Experiment: Compressibility, Sweep, Rate, Waveform, and Geometry Effects on Unsteady Separation and Dynamic Stall,” Technical Report, DTIC Document No. UTRC R92-958325-6.
Desgeorges, O., Lee, T., and Kafyeke, F., 2002, “Multiple Hot-Film Sensor Array Calibration and Skin Friction Measurement,” Exp. Fluids, 32(1), pp. 37–43. [CrossRef]
Kunkel, G., and Marusic, I., 2003, “An Approximate Amplitude Attenuation Correction for Hot-Film Shear Stress Sensors,” Exp. Fluids, 34(2), pp. 285–290. [CrossRef]
Alfredsson, P., Johansson, A., Haritonidis, J., and Eckelmann, H., 1988, “The Fluctuating Wall-Shear Stress and the Velocity Field in the Viscous Sublayer,” Phys. Fluids, 31, p. 1026. [CrossRef]
Kolmogorov, A., 1941, “The Local Structure of Turbulence in Incompressible Viscous Fluid for Very Large Reynolds Numbers,” Proc.: R. Soc. Edinburgh, Sect. A: Math. Phys. Sci., 434(1890), pp. 9–13. [CrossRef]
Burgmann, S., Brücker, C., and Schröder, W., 2006, “Scanning PIV Measurements of a Laminar Separation Bubble,” Exp. Fluids, 41(2), pp. 319–326. [CrossRef]
Huang, R., Shy, W., Lin, S., and Hsiao, F., 1996, “Influence of Surface Flow on Aerodynamic Loads of a Cantilever Wing,” AIAA J., 34(3), pp. 527–532. [CrossRef]
Shan, H., Jiang, L., and Liu, C., 2005, “Direct Numerical Simulation of Flow Separation Around a NACA 0012 Airfoil,” Comput. Fluids, 34(9), pp. 1096–1114. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Aerodynamic efficiency of smooth airfoils as a function of the chord-based Reynolds number. (Adapted from McMasters and Henderson [3].)

Grahic Jump Location
Fig. 2

Picture of the test section and the instrumented airfoil

Grahic Jump Location
Fig. 3

Short sample of hot-film voltages near separation

Grahic Jump Location
Fig. 4

Cross correlation coefficient for the static case

Grahic Jump Location
Fig. 5

Spectra of the hot-film signals before and after separation

Grahic Jump Location
Fig. 6

Trailing edge power spectra behind the sensor and the smooth area for α = 0

Grahic Jump Location
Fig. 7

Hot-film signals (left) and corresponding spectra (right)

Grahic Jump Location
Fig. 8

Hot-film voltage signals at a 0 deg angle of attack

Grahic Jump Location
Fig. 9

Hot-film quasi-static signals

Grahic Jump Location
Fig. 10

Cross correlation coefficient for the quasi-static case

Grahic Jump Location
Fig. 11

Separation and transition localization on the airfoil surface; the dotted line represents the oil-flow results of Huang et al. [22]

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In