Profile and Mixing Losses of a Turbine Cascade Under the Condition of Low Reynolds Number Flows

Systematic flow measurements of profile and mixing losses were made across the blade pitches of a linear turbine cascade at low and moderate Reynolds numbers. The effect of Reynolds number on mixing behavior and development of the wake downstream of the trailing edge were investigated by means of traverse results at different planes downstream of the cascade. The experimental loss data were compared with predictions of theoretical boundary layer flow methods and of computational fluid dynamics (CFD) analyses. Several turbulence models available in commercial CFD tools and in the open CFD code OpenFOAM were considered for the present case study. It was found that substantial deviations between the numerical predictions and the experimental data occurred. These deviations may be attributed to the fact that at low Reynolds numbers, laminar and transitional boundary layer flows and flow separation phenomena became relevant. Based on the experimental two-dimensional loss data, the validity of simple Reynolds number scaling rules was assessed.