1. Flow Solver All numerical results presented in this paper have been carried out using the flow solver TRACE developed by DLR Cologneand MTU AeroEngines, which is optimized for turbomachinery internal flows. The code solves the unsteady Reynolds averaged Navier-Stokes equations by means of a finite volume approach on multi-block structured grids. All convective fluxes are discretized using the TVD upwind scheme by Roe, which is combined with a MUSCL extrapolation scheme to gain second order accuracy in space. On the other hand all diffusive fluxes are discretized using a second order central differencing scheme. Furthermore non-reflecting inflow and outflow boundary conditions are implemented. Although the code is time-accurate in general only steady state simulations have been performed within this study. Therefore a time marching technique with an implicit predictor corrector scheme has been used. Turbulent flow is taken into account by using the Wilcox k -ω turbulence model11with some special modifications regarding the 'stagnation point anomaly' and effects caused by compressibility and rotation. Further modifications are caused by the implementation of the transition model described below. For any more detailed information about TRACE please refer to the corresponding references.12-15
2. In order to get detailed information about the flow characteristics, 3D hot wire anemometry has been used for measuring the turbulence intensity at 55 positions symmetrically around the center of the wind tunnel nozzle (see Fig. 8). This gives information about the overall turbulence level as well as about the homogeneity of turbulence.150 -100 -50 0 50 100 150 -100