Transonic flutter computations for the NLR 7301 supercritical airfoil

A numerical investigation of the transonic steady-state aerodynamics and of the two-degree-of-freedom bending/torsion flutter characteristics of the N LR 7301 section is carried out using a time-domain method. An unsteady, two -dimensional, compressible, thin-layer Navier-Stokes flow-solver is coupled with a two-degree-of-freedom structural model. Fully turbulent flows are c omputed with algebraic or one-equation turbulence models. Furthermore, natu ral transition is modeled with a transition model. Computations of the stea dy transonic aerodynamic characteristics show good agreement with Schewe's experiment after a simplified accounting for wind-tunnel interference effec ts is used. The aeroelastic computations predict limit-cycle flutter in agr eement with the experiment. The computed flutter frequency agrees closely w ith the experiment but the computed flutter amplitudes are an order of magn itude larger than the measured ones. This discrepancy is likely due to the omission of the full wind-tunnel interference effects in the computations. (C) 2001 Editions scientifiques et medicales Elsevier SAS.