Unsteady transonic flow over wings including inviscid/viscous interaction

Abstract

A numerical procedure is presented for computing the unsteady transonic flowfield about swept wings undergoing time-dependent motions. The outer inviscid portion of the flow is assumed to be governed by the modified unsteady transonic small disturbance potential equation which is integrated in the time domain by means of an alternating direction implicit algorithm. Dominant effects of the shock/boundary-layer interaction are accdunted for by a simple empirically defined model. Viscous flow regions adjacent to the wing surface and in the trailing wake are described by a set of integral equations appropriate for compressible turbulent shear layers. The two-dimensional boundary-layer equations are applied quasistatically stripwise across the span. Coupling with the outer inviscid flow is implemented through use of the displacement thickness concept. Validity of the assumptions underlying the method is established by comparison with experimental data for the flow about a high aspect ratio transport wing having an advanced airfoil section.