Design and Aeroelastic Assessment of a Forward Swept Wing Aircraft

摘要

Aeroelastic effects strongly influence the design of an aircraft. To be able to assess those effects early on, reliable simulation models representing the global aeroelastic properties of a new design are required. At a conceptual or a pre-design stage, an intelligent parameterization concept allows for limited changes of the configuration while the simulation models are adapted accordingly. In the DLR project iGREEN (Integrated Green Aircraft), the goal was to investigate the impact of technologies for the reduction of fuel consumption on the aeroelastic properties of aircraft. One main aspect was the influence of laminar wing design on divergence, flutter and dynamic loads. As the reference aircraft in the project, the concept of a forward swept wing aircraft with rear-mounted engines has been analyzed. An aeroelastic model has been built up in the project. The model design procedure is based on the DLR in-house tool set MONA (ModGen/NASTRAN). Focus of this design process is the generation of a parameterized structural model, representing the global dynamic properties of the elastic aircraft, but as detailed as reasonable in order to capture relevant local effects and to result in a feasible structural design. In the course of the work, the operational envelope of the aircraft as well as the resulting points for aeroelastic and loads analysis have been derived. A parameterized global finite element model of the aircraft has been built up, and the wing and the empennage structure have been sized based on a selected number of realistic load cases. Finally, aeroelastic analyses have been performed, consisting of divergence analyses, dynamic loads analyses, and an investigation of the influence of the gyroscopic effects of the engines on the flutter behaviour. In the paper, the aircraft design is presented. The modelling and sizing process for the structure is described. Results of the loads analysis as well as of the aeroelastic stability analyses are discussed.