Unsteady aerodynamics of Wortmann FX63-137 airfoil at low Reynolds numbers.

Abstract

Unsteady pressure data are discussed for a two-dimensional Wortmann FX63-137 airfoil at Reynolds numbers 125000 and 400000, alpha=0deg, and over a range of reduced frequencies, kappa, from 0.15 to 6.4. Unsteady boundary layer data near the region of laminar separation are also presented for RE=125000, k=0.15 and 2.0. Surface pressure data show that the unsteady excitation imposed interact most actively in the transition region with large amplitude and higher harmonics. Unsteady boundary layer results in the region of laminar separation reveal that the time mean unsteady velocity profile for both reduced frequencies tested are quite similar. The ensemble averaged profiles for k=0.15 suggest that the unsteady boundary layer tends to be more attached when the free stream velocity is a minimum. Data show that this effect is less pronounced at k=2.0. (A)