Time-Linearized Transonic Computations Including Shock Wave Motion Effects

Abstract

The effect of small perturbations on steady nonlinear transonic flowfields, in the context of two-dimensional flows governed by the general-frequency transonic small disturbance equation with nonreflecting far-field boundary conditions, is studied. Numerious existing time-linearized frequency-domain methods have failed to account for the shock wave motion that is known to occur. A time-linearized time-domain method, incorporating a procedure referred to as the shock jump correction procedure, is presented. This procedure allows one to account for correctly small-amplitude shock wave motions due to small unsteady changes in the airfoil boundary conditions. First harmonic pressure distributions and airloads for a NACA 64A006 airfoil with an oscillating quarter-chord flap are predicted and compared with those obtained from the time-linearized frequency-domain and nonlinear schemes and experiments