At high angles of attack and very high flight speeds, conventional, fast loads analysis methods become invalid. In this case, it is advisable to carry out analyses by means of direct simulation of CFD, structural dynamics and flight mechanics. The advantage of this approach is that all of the physical effects that are described by the CFD code and the structural solver can be taken into account. However, this results in very large simulation models and extremely long computation times. In the DLR project Digital X, and in the LuFo IV project AeroStrukt, methods for coupled simulations have been developed and carried out at the Institute of Aeroelasticity. These methods use the DLR TAU code and are integrated into FlowSimulator as a module (FSDynafly) in cooperation with the Institute of Aerodynamics and Flow Technology.
An example of the application of this method is the CFD4Loads workshop, which was initiated by Airbus UK. The background to this was the desire by Airbus to obtain an overview of the aeroelastic simulation capabilities of major European aeronautics research facilities. For this, structural models and geometrical data of a current aircraft configuration were provided. Due to its profound expertise in simulation technologies DLR was capable of processing all of the defined reference cases. In a cooperation between the Institute of Aeroelasticity and the Institute of Aerodynamics and Flow Technology, extensive simulations of flights through gusts by the flexible aircraft were carried out within the Digital X project.
Further ongoing work is concerned with the integration of flight and load controllers into the CFD simulation, as well as investigation of the effect of very large wing deformations on flight loads.