Wake analysis of a plunging airfoil

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.An experimental measurements of unsteady wakes behind a sinusoidally plunging airfoil was surveyed with a Hot-wire rake containing seven I-wires. The aim of these measurements was to study the velocity profiles behind the oscillating airfoil trailing edge. Influences of reduced frequency and angle of attack were studied in details. It was shown that the angle of attack and reduced frequency are the most important parameters which influence on the velocity profiles. The momentum deficit was relative to reduced frequency and amplitude of oscillation and its behaviours were changed after static stall angles. At the angle of attack beyond static stall angle flow separation causes increasing the momentum deficit. The velocity profile has approximately symmetric shape profile. Data were taken at mean incidence angles of 0, 8 degrees at reduced frequencies of 0.09 to 0.56. The nondimensional amplitude of oscillation was 0.27. The corresponding Reynolds numbers, based on the chord length, were 25000 and 150000.