LINEAR FREQUENCY DOMAIN PREDICTIONS OF DYNAMIC DERIVATIVES FOR THE DLR F12 WIND TUNNEL MODEL

Abstract

Structural loads for full aircraft configurations can be represented by evaluating dynamic derivatives over a wide parameter space mainly including different mode shapes, an- gle of attack and Mach numbers. Traditionally, these values are determined by wind tunnel tests applying forced periodic motions to aircraft models. The ability of numerical simula- tions provide an excellent addendum to wind tunnel tests. Instead of time-accurate unsteady Reynolds-averaged Navier-Stokes (URANS) solvers which are recognized as extremely compu- tational expensive this paper considers a linearized frequency domain solver (LFD). With this approach the unsteady simulation reduces to a single steady state computation and a single linear simulation in the frequency domain. By the assumption of small perturbations and har- monic oscillations dynamic derivatives can be computed efficiently within a wide parameter space. In addition, the theoretical background for the LFD will be presented. Based on the linearization of the RANS equations and modeling of small perturbations with Fourier series a complex valued linear system has to be solved.