Hostname: page-component-848d4c4894-x5gtn Total loading time: 0 Render date: 2024-05-03T05:17:26.505Z Has data issue: false hasContentIssue false
  • English
  • Français

Unsteady laminar separation: an experimental study

Published online by Cambridge University Press:  19 April 2006

C. A. Koromilas  and
D. P. Telionis
C. A. Koromilas
Affiliation:
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, U.S.A.
D. P. Telionis
Affiliation:
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, U.S.A.
Get access Rights & Permissions [Opens in a new window]

Abstract

The design of most aerodynamic surfaces, as for example the helicopter rotor, is based essentially on quasi-steady theories. However, the dynamics of a rotating blade introduce unexpected fluctuations and overshoots of properties like lift, drag, etc. The phenomenon of unsteady stall is intimately connected with the development of an oscillating boundary layer and separation. Experimental investigation of such flows was undertaken by a method of visualization developed especially for the study of laminar or turbulent boundary layers and separation. The method captures the instantaneous two-dimensional flow field, including regions of separated flow, and provides accurate quantitative information. Laser-doppler anemometer measurements complement the optically obtained data. Results reveal that separation responds with time-lag to external disturbances, in agreement with unsteady stall data. Oscillating outer flows result in displacement of the point of separation and, under certain conditions, the Despard & Miller (1971) criterion was found to hold. Earlier theoretical models of separation are confirmed qualitatively and for the early stages of the transient phenomena. The findings provide physical insight and quantitative data that may help explain the phenomenon of unsteady stall and unsteady separation.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 97 , Issue 2 , 25 March 1980 , pp. 347 - 384
Copyright
© 1980 Cambridge University Press

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.)

References

Carr, L. W., McAlister, K. W. & McCroskey, W. J. 1977 Analysis of the development of dynamic stall based on oscillating airfoil experiments. N.A.S.A. Tech. Note NASA TN D8382.
Despard, B. A. & Miller, J. A. 1971 J. Fluid Mech. 47, 21.
Face, A. 1934 Proc. Roy. Soc. A 144, 381.
Fansler, K. S. & Danberg, J. E. 1976 A.I.A.A. J. 14, 1137.
Homann, F. 1937 Forsch. Geb. Ing. Wes. 7, 1.
Kenison, R. C. 1977 An experimental study of the effect of oscillatory flow on the separation region in a turbulent boundary layer. In Unsteady Aerodynamics, AGARD-CP-227, paper no. 20.
Ludwig, G. R. 1964 A.I.A.A. Paper no. 64-6.
McAlister, K. W. & Carr, L. W. 1978 Water tunnel experiments on an oscillating airforl at Re = 21000. N.A.S.A. NASA TM 78446.
McAlister, K. W., Carr, L. W. & McCroskey, W. J. 1978 Dynamic stall experiments on the NACA 0012 airfoil. N.A.S.A. Tech. Paper 1100.
McCroskey, W. J. 1971 In Fluid Dynamics of Unsteady, Three-Dimensional and Separated Flow (ed. F. J. Marshall), Project SQUID, Purdue University, p. 346.
McCroskey, W. J. 1972 In Aerodynamics of Rotary Wings, AGARD Conf. Proc. 3, 17.
McCroskey, W. J. 1977 Trans. A.S.M.E. I, J. Fluids Engng 99, 8.
Mehta, U. B. 1977 Dynamic stall of an oscillating airfoil. In Unsteady Aerodynamics, AGARD-CP-227, paper no. 27.
Mehta, U. B. & Lavan, Z. 1975 J. Fluid Mech. 67, 227.
Moore, F. K. 1958 In Boundary Layer Research (ed. H. Görtler), p. 296. Springer.
Prandtl, L. 1904 In Proc. Intern. Math. Congr. i Br., p. 484.
Pruppacher, H. R., Le Clair, B. P. & Hamielec, A. E. 1970 J. Fluid Mech. 44, 781.
Rott, N. 1956 Quart. appl. Math. 13, 444.
Rott, N. 1964 In Theory of Laminar Flows (ed. F. K. Moore), p. 395. Princeton University Press.
Ruiter, G. H., Nagib, H. M. & Fejer, A. A. 1971 In Fluid Dynamics of Unsteady, Three-Dimensional and Separated Flow (ed. F. J. Marshall), p. 423.
Sandborn, V. A. 1969 Characteristics of boundary layers at separation and reattachment. College of Engng, Colorado State Univ., Res. Memo. no. 14.
Sandborn, V. A. & Liu, C. Y. 1968 J. Fluid Mech. 32, 293.
Schraub, F. A., Kline, S. J., Henry, J., Rumstadler, P. W. & Littel, A. 1965 Trans. A.S.M.E. D, J. Basic Engng 87, 429.
Sears, W. B. 1956 J. aeronaut. Sci. 23, 490.
Sears, W. R. & Telionis, D. P. 1971 In Recent Research of Unsteady Boundary Layers (ed. E. A. Eichelbrenner), vol. 1, p. 404. Laval University.
Sears, W. R. & Telionis, D. P. 1975 SIAM J. appl. Math. 28, 215.
Shen, S.-F. 1978 Adv. appl. Mech. 18, 177.
Simpson, R. L. 1977 Features of unsteady turbulent boundary layers as revealed from experiments. In Unsteady Aerodynamics, AGARD-CP-227, paper no. 19.
Taneda, S. 1971 In Recent Research on Unsteady Boundary Layers (ed. E. A. Eichelbrenner), vol. 2, p. 1165. Laval University Press.
Telionis, D. P. 1970 Boundary layer separation. Ph.D. thesis, Cornell University.
Telionis, D. P. 1975 A.I.A.A. J. 13, 1979.
Telionis, D. P. 1977 Unsteady boundary layers separated and attached. In Unsteady Aerodynamics, AGARD-CP-227, paper no. 16; also Trans. A.S.M.E. I, J. Fluids Engng 101, 29.
Telionis, D. P. & Koromilas, C. A. 1978 Experimental investigation of unsteady separation. VPI & SU Engng Rep. no. VPI-E-78-24.
Telionis, D. P. & Werle, J. 1973 Trans. A.S.M.E. E, J. Appl. Mech. 95, 389.
Tennant, J. S. 1973 A.I.A.A. J. 11, 240.
Tennant, J. S. & Yang, T. 1973 A.I.A.A. J. 11, 1156.
Tsahalis, D. Th. 1976 A.I.A.A. J. 15, 561.
Tsahalis, D. Th. & Telionis, D. P. 1974 A.I.A.A. J. 12, 1469.
Vidal, J. R. 1959 Research on rotating stall in axial-flow compressors. Wright Air Development Center, Wright-Patterson Air Force, Base, Rep. Part III. WADC TR-59-75.
Wérlé, H. 1973 Ann. Rev. Fluid Mech. 5, 361.
Williams, J. C. 1977 Ann. Rev. Fluid Mech. 9, 113.