Unsteady Transonic Flows over an Airfoil

Abstract

Inviscid, transonic flows over the NACA 64A410 airfoil were calculated using a finite-difference analog of the Euler equations. Steady flow solutions were obtained for angles of attack of 0°, 2° and 4° at Mach 0.72. Unsteady calculations were made at the same Mach number and in the same general angle-of-attack range for a step change of angle of attack, a step change in pitching angular velocity, and for sinusoidal pitching oscillations about the midchord at reduced frequencies 0.2,1.0, and 5.0. (Reduced frequency, K^uC/U^.) A summary of the resulting surface pressures, shock locations, and the forces and moments is presented. The forces and moments obtained for the cases with harmonic oscillations were compared to the results from a linearized analysis which used, to approximate the indicial functions, the responses calculated for the step changes.