KSME International Journal

, Volume 16, Issue 10, pp 1303–1313 | Cite as

Frequency effects of upstream wake and blade interaction on the unsteady boundary layer flow



Effects of the reduced frequency of upstream wake on downstream unsteady boundary layer flow were simulated by using a Navier-Stokes code. The Navier-Stokes code is based on an unstructured finite volume method and uses a low Reynolds number turbulence model to close the momentum equations. The geometry used in this paper is the MIT flapping foil experimental set-up and the reduced frequency of the upstream wake is varied in the range of 0.91 to 10.86 to study its effect on the unsteady boundary layer flow. Numerical solutions show that they can be divided into two categories. One is so called the low frequency solution, and behaves quite similar to a Stokes layer. Its characteristics is found to be quite similar to those due to either a temporal or spatial wave. The low frequency solutions are observed clearly when the reduced frequency is smaller than 3.26. The other one is the high frequency solution. It is observed for the reduced frequency larger than 7.24. It shows a sudden shift of the phase angle of the unsteady velocity around the edge of the boundary layer. The shift of phase angle is about 180 degree, and leads to separation of the boundary layer flow from corresponding outer flow. The high frequency solution shows the characteristics of a temporal wave whose wave length is half of the upstream frequency. This characteristics of the high frequency solution is found to be caused by the strong interaction between unsteady vortices. This strong interaction also leads to destroy of the upstream wake strips inside the viscous sublayer as well as the buffer layer.

Key Words

Unsteady Boundary Layer Flow MIT flapping foil Reduced Frequency 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Choi, J. E., Sreedhar, M. K., Stern, F., 1996, “Stokes Layers in Horizontal Wave Outer Flows,” ASME J. Fluids Engineering, Vol. 118, pp. 537–545.CrossRefGoogle Scholar
  2. Gissing, J. P., 1969, “Vorticity and Kutta Condition for Unsteady Multi-Energy Flow,”ASME J. Applied Mechanics, Vol. 36, pp. 608–613.Google Scholar
  3. Horlock, J., 1968, “Fluctuating Lift Forces on an Airfoils Moving through Transverse and Chordwise Gusts,”ASME J. Basic Engineering, pp. 494–500.Google Scholar
  4. Horwich, E. A., 1993, “Unsteady Response of a Two Dimensional Hydrofoil Subject to High Reduced Frequency Gust Loading,” M. S. Thesis, Dept. of Ocean Eng., MIT, Cambridge, MA.Google Scholar
  5. Kang, D. J., Bae, S. S., and Joo, S.W., 1998, ”An Unstructured FVM for the Numerical Prediction of Imcomressible Viscous Flows,“Transactions of the KSME, Vol. 22, No. 10, pp. 1410–1421.Google Scholar
  6. Kang, D. J., Bae, S. S., 1999a, “Navier-Stokes Simulation of MIT FFX by Using an Unstructured Finite Volume Method,”ASME Turbo-Expo IGTI-99-214.Google Scholar
  7. Lee, Y. T., Kirtis, C, Rogers, S. E., Zawadzki, I. and Kwak, D., 1995, “Steady and Unsteady Multi-Foil Interactions by Navier-Stokes and Eu-ler Calculations,”Unsteady Aerodynamics and Aeroelasticity of Turbomachines, Elsevier Science, pp. 93–107.Google Scholar
  8. Paterson, E. G. and Stern, F., 1999, “Computation of Unsteady Viscous Marine Propulsor Blade Flows-Part 2: Parametric Study,”ASME J. Fluids Engineering, Vol. 121, pp. 121–147.Google Scholar
  9. Poling, D. R. and Telionis, D. P., 1986, “The response of Airfoils to Periodic Disturbances- The Unsteady Kutta Condition,”AIAA J. Vol. 24. No. 2, pp. 193–199.CrossRefGoogle Scholar
  10. Rice, J. Q., 1991, “Investigation of Flows around a Two-dimensional Hydrofoil in Steady and Unsteady Flows,” M. S. Thesis, Dept. of Ocean Eng., MIT, Cambridge, MA.Google Scholar
  11. Tsahalis, D. Th. and Telionis, D. P., 1974, “Response of Separation to Impulsive Changes of Outer Flow,”AIAA J. Vol 12, pp. 614–619.MATHCrossRefGoogle Scholar
  12. Thomadakis, M. and Leschziner, M., 1996, “A Pressure Corection Method for the Solution of Incompressible Viscous Flows on Unstructured Grids,“Int. J. Nume. Methd. in Fluids, Vol. 22, pp. 581–601.MATHCrossRefGoogle Scholar
  13. Stern, F., Hwang, W. S. and Jaw, S. Y., 1989, “Effects of Waves on the Boundary Layer of Surface Piercing Flat Plate: Experiment and Theory,”J. Ship Research, Vol. 33, pp. 63–68.Google Scholar

Copyright information

© The Korean Society of Mechanical Engineers (KSME) 2002

Authors and Affiliations

  1. 1.School of Mechanical EngineeringYeungnam UniversityKyungbukKorea

Personalised recommendations