Effect of vortex shedding in unsteady aerodynamic forces for a low Reynolds number stationary wing at low angle of attack

A. Villegas, F. J. Diez

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

This study elucidates the relation between wake vortex shedding and aerodynamic force fluctuations for a low Reynolds number wing from time resolved particle image velocimetry (TR-PIV) experimental measurements. The results reveal a periodic lift and drag variation within the shedding cycle and resolve the frequencies of those fluctuations from a proper orthogonal decomposition (POD) and power spectral density (PSD) analysis. To show the effect of vortex shedding on the body force fluctuations, the evolution of instantaneous aerodynamic forces is compared to the pressure field of the fluid flow and to the vortical structures in the wake of the airfoil. A six step model describing the vortex-force relation is proposed. It shows that changes in lift such as maximum lift and minimum lift are associated with the detachment of a vortex. It also shows that the minimum or local minimum drag value is obtained at the onset formation of a vortex on the airfoil wake. Similarly, the maximum or local maximum drag is obtained at the onset formation of the saddle on the airfoil wake. The model further explains the asymmetry observed in the unsteady drag force evolution. The model can be used to optimize flow control and fluid-structure interaction applications.

Original languageEnglish (US)
Pages (from-to)138-148
Number of pages11
JournalJournal of Fluids and Structures
Volume64
DOIs
StatePublished - Jul 1 2016

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Keywords

  • Particle image velocimetry
  • Proper orthogonal decomposition
  • Unsteady forces
  • Vortex shedding

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