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Content archived on 2024-05-29

Turbulence and Transition Modelling for Special Turbomachinery Applications

Final Report Summary - TATMO (Turbulence and Transition Modelling for Special Turbomachinery Applications)

The main objectives of the TATMO project were concerned with the improvement of calculation capabilities by a better modelling of the flow with and without span-wise roughness elements and synthetic jets in axial flow, multistage turbines and compressors with a certain emphasis on LP turbines at very low Reynolds numbers.

The consortium of 16 partners from industry, research institutions, and universities representing 6 countries focused their research on the validation of Navier-Stokes codes with turbulence models including transition models in comparison with thoroughly performed detailed cascade experiments. The partners concentrated their model development primarily on codes, which are actually used in the industry, and consciously ignored the rapidly advancing DNS capabilities for this project to allow for proper implementation of the results. Comparisons of global parameters and local distributions of flow variables have been made in the course of the validation work of the project.

The global parameters such as cascade loss and exit angle are documenting correct values in comparison with the measurements for all Reynolds-numbers and for all investigated designs with different pressure distributions thus demonstrating the considerable improvement of the developed turbulence models. Even local distributions such as the pressure along the surfaces of the blade are now revealing a perfect match with the experiment.

However, the pitchwise total pressure loss distribution is not yet showing satisfactory results for all Reynolds numbers. This distribution was measured in parallel to the blade row at a certain distance behind the trailing edge. In particular the wake profile sometimes still changes for calculations with different grid extension behind the trailing edge at the measurement location.

The calculated wake profile was often too deep and less wide relative to the measurement at low Reynolds-numbers. Therefore, the improved reproduction of wake decay is subject for future research. Additionally the comparison of synthetic jet / separation bubble interaction at realistic Mach-numbers remains a challenge for the future.