Measured pressure distributions on an airfoil with oscillating jet flap

The experiments described, in conjunction with an earlier study by the author, comprise a set which enables the prediction of aerodynamic forces and moments on a two-dimensional airfoil undergoing general motions involving small displacements. The magnitude and phase angle of aerodynamic derivatives generated on a fixed airfoil by small oscillations of a jet flap at the trailing edge have been measured in incompressible flow. Results are presented for a range of frequency of oscillation and strength of the jet and Reynolds number. The apparatus and techniques used to obtain oscillatory surface pressure distributions are described. The measurements reported agree well with the majority of other experimental data. The trends are predicted by the theory of Potter, but not by the theory of Spence which should be applied only for much higher dimensionless frequencies than those used in the experiments