Aerodynamic Influence Coefficients from the Unsteady Transonic Small Disturbance Equation for Aeroelastic Analysis

A methodology to compute the transonic aerodynamic influence coefficients from the unsteady transonic small disturbance (TSD) equation is presented. Solution of the unsteady TSD equation is performed using a finite-difference discretization with a time-domain approximate-factorization algorithm. The aerodynamic influence coefficients are computed as a function of Mach number and reduced frequency by performing a linearization of the unsteady TSD equation about a steady-state solution which captures the nonlinear behavior of the transonic flow. The unsteady transonic aerodynamic influence coefficients matrices are integrated into NASTRAN using Direct Matrix Input for use in static aeroelastic and flutter analyses. Validation of the predicted aerodynamics is performed on a rectangular wing as well as the F5 wing planform.