A Krueger flap and corresponding kinematics has been designed for the DLR-F15-LLE airfoil. Realistic design requirements from aircraft level have been specified and respected. The design has been performed in a loop where side constraints on kinematics have been developed and included in the aerodynamic design. The Kreuger flap and the kinematics have been implemented in the wind tunnel model design. Further on, the speed of deployment and retraction of the Krueger device have been established. These numbers reflect the manufacturer knowledge on handling quality and certification criteria for Krueger devices.
The simulation methods have been setup for designated simulation type. On grid generation side, a robust implementation of local reconnection algorithm for unstructured meshes was obtained. Further, a demonstration of local-grid refinement in conjunction with Chimera capability on structured meshes has been established. Beside this, Immersed Boundary Methods and full re-meshing has been successfully applied. With regard to flow solver technologies, most of the partners have demonstrated their capabilities of simulating the deployment of the Krueger device. Methods in use range from uRANS methods via different turbulence-resolving methods (hybrid RANS/LES) up to particle based Lattice Boltzmann Methods.
The modifications for both wind tunnel models have been designed and manufactured. Finite Element Analysis has been used to complete corresponding stress reports. The models are equipped with a significant number of unsteady pressure sensors for dynamic measurements. The PIV methodology to be used to monitor the dynamic flow field has been selected and the implementation in terms of measurement window as well as hardware setup in the tunnel has been achieved. As there are a number of different measurement systems, a synchronisation approach has been established, including trigger, automation and communication approaches.
In total, five wind tunnel tests have been conducted in three different wind tunnel facilities. A first exploratory test entry in ONERA-L1 provided experience on the model behaviour, revealed critical areas in routing sensor connections and proved at first the baseline conditions in first glance comparison of CFD and PIV data based on steady flow conditions. The wind tunnel test in DNW-NWB with a straight and swept cantilever wing arrangements were fully completed. A first entry has finally been conducted in DNW-LLF for the pressure and deformation measurements. Completing the high quality data base, detailed PIV measurements have been conducted in a second entry within both, the ONERA-L1 and the DNW-LLF facility.
In order to compare numerical and experimental data, guidelines for validation have been compiled. By specifying common formats and templates, a common ground for comparison was established. Specific simulations of the different wind tunnel setups were performed, especially using real-time recorded data of the drive system to closely match the real deflection process. Validation of the simulation methods has been achieved and the combination of both data sources has been used to derive important flow features of the Krueger flap for aircraft application.
