Vortices generated and designed in internal cooling systems of film cooled turbine blades have a significant influence on the aerodynamic mixing process of the coolant and the main flow. Of course the resulting distribution of the film cooling effectiveness is strongly influenced by the behaviour of the coolant mixing. The vortices are generated by a special design of the cooling channel and film cooling holes and by the comparable flow phenomena coming along with the problem of jets in crossflow.

The multi-block Navier-Stokes solver TRACES with special features for the simulation of complex and turbulent mixing phenomena is applied to solve the flow field and the heat fluxes and temperature distribution in the turbine blade structure simultaneously. The code is validated for the simulation of film cooling and heat transfer and was also compared to other codes taking part in the AGARD Working group 26 (Dunham, 1996 [4]) working on the test cases “NASA-Rotor-37” and DLR-Turbine guide vane “VT1B”.

As a result of extensive parameter studies (Vogel, 1996 [18]) a vortex mixing model will be established which describes the existing vortices and their effect on the film cooling mixing process in detail. It was found that vortex generation inside the internal cooling channel with an opposite direction of rotation compared with the main kidney shaped jet vortex system can reduce the amount of coolant air significantly without reducing the film cooling effectiveness. All numerical investigations presented in this paper were carried out using a model geometry. No experimental results were available for this geometry. The validation of the code concerning film cooling mixing was presented in [15], [16], [17] and [18] (Vogel, 1994–1996). The geometries applied in those validations were quite similar to those used in this paper. Nevertheless for credibility some comparisons between experimental and numerical data are presented.

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