Christian Morsbach

Application of a Low Reynolds Differential Reynolds Stress Model to a Compressor Cascade Tip-Leakage Flow

The tip-leakage flow of a low speed compressor cascade at Ma = 0. 07 and Re = 400, 000 was simulated employing the Jakirlic/Hanjalic-ω h (JH-ω h ) differential Reynolds Stress model (DRSM) and results are presented. The predictions are compared with those obtained using the SSG/LRR-ω DRSM and the Menter SST k-ω linear eddy viscosity model (LEVM). In addition to the mean flow quantities, the focus is on the Reynolds stresses and their anisotropy. Both DRSMs show significant improvements compared to the LEVM with respect to the mean flow quantities; however, details of the turbulence structure are more accurately predicted by the JH-ω h model.

Using automated optimisation to calibrate a correlation-based transition model

Transition models used in turbomachinery CFD are based on empirical correlations de-rived from a series of fundamental test cases. When these models are applied to complex configurations they often do not perform as desired and need to be tuned to the respec-tive area of application. In this paper, an approach to tune a correlation based transition model to a given set of turbine rigs using automated optimisation is presented. The model is optimised such that deviations from experiments in terms of blade pressure distribution and global losses are minimised. The optimisation strategy and results are analysed in detail showing strengths and weaknesses of the proposed approach. While the agreement with experimental data of the turbine rigs can be improved, an analysis of zero pressure gradient flat plate flow shows that the resulting models cannot be considered as general as the original model.