Application of Advanced CFD Tools for High Reynolds Number Testing.

Numerical simulations of the DLR F11 high lift half model in landing configuration in the test section of the ETW wind tunnel have been carried out with the unstructured CFD code DLR TAU. The numerical results are compared to measurements of the cryogenic wind tunnel ETW performed within the EU project FLIRET. The tests have been conducted with three different peniche heights of the F11 model to determine the influence of the so called half model mounting effects on the aerodynamic characteristics of model flow. Based on the numerical simulation of the half model tests the peniche effects and the wind tunnel flow itself are analyzed. The capability of the used CFD code for high Reynolds number testing is demonstrated

Aerodynamic Analysis of Flows with Low Mach- and Reynolds-Number under Consideration and Forecast of Transition on the Example of a Glider

For the simulation of low Reynolds- and Mach number flows, a boundary layer code in combination with a database method are coupled with an unstructured RANS code. The technique is validated in 2D using a glider airfoil and in 3D for a glider, showing good agreement with experiments and a well-validated 2D design code

Premature decay of wake vortices with Differential- and Oscillating Flap Setting

This paper gives an overview of the research on wake vortex decay using Differential Flap Setting (DFS) and Oscillating Flap Setting (OFS). The concept of DFS deals with the small deflection of flaps and elevator to produce additional vortices which interacts with the vortices from wing, elevator, flaps and wing-body-junction. Numerical calculations with the A340-300 model at this topic are presented in the first part of the paper. On the other hand the OFS concept works with the periodic movement of DLC (direct lift control) flaps and/or ailerons to trigger inherent instabilities of the vortices. The basic mechanism of the introduction of the periodic disturbance into the flow field is a periodic alternation of the spanwise lift distribution, i.e. of the circulation and spacing ratios of the distinct vortex pairs in the extended wake vortex nearfield. This can be achieved both by pitch oscillation and oscillating DLC flaps. Pitch oscillation alone are sufficient for accelerating Crow instability as proven already in the 1970s with small aircraft. One can distinguish between long-wavelength and short-wavelength instabilities. The second part of this paper is truncated on short-wavelength instability examinations i.e. the Crow instability