Transonic Flutter Calculations for the AMP Wind Tunnel Model with Engine Pylons and Nacelles

Abstract

In order to investigate aeroelastic aspects of engine/airframe integration, a simulation chain is set up capable of conducting high-fidelity transonic flutter calculations for aircraft configurations with engine pylons and nacelles. For that purpose, a combination of several software systems is used: DLR’s unstructured TAU code for steady RANS calculations, the Transonic Doublet Lattice Method (TDLM) for unsteady linearized potential flow computations, and a p-k flutter solver for frequency domain flutter analysis. The computational approach is demonstrated for the AMP wind tunnel model. Flutter boundaries are presented and validated with experiment for three different configurations, and are compared to investigate the influence of the inclusion of engine pylons and nacelles onto the predicted flutter boundary. It is shown that the inertial contribution from the engine masses has a significant destabilizing effect. Inclusion of the unsteady nacelle airloads is shown to lead to a further reduction of the flutter stability.