Computation of the Flutter Boundary of the NLR 7301 Airfoil in the Transonic Range

Abstract

Aerodynamic simulations were performed in order to compute the unsteady load response of the NLR 7301 airfoil for heave and pitch oscillations in the transonic range. The data were used to determine the aeroelastic flutter boundary of a recangular two degree of freedom wing. On the one hand the DLR TAU code was used to solve Reynolds averaged Navier-Stokes (RANS) equations applying the Spalart-Allmaras an k-w turbulence models. On the other hand computations were made with the DLR TDLM code, which solves the time linearized transonic small disturbance (TSD) equation. The settings were chosen according to experiments by Dietz et al. [1] in the Transonic Wind Tunnel Goettingen (TWG). The comparison between the computed and the experimental results showed that the simulation codes are capable of computing reliable results. Characteristic transonic aeroelastic phenomena were found. The appropriate modeling of viscous effects in transonic flow showed out to be an indispensable condition.