Numerical Assessment of Eddy-Viscosity Turbulence Models of an Axial-Flow Turbine at a Low Reynolds Number

The flow field behavior of axial flow turbines is of great importance, especially in
modern designs that may operate at a low Reynolds number. At these low Reynolds
numbers, the efficiency loss is significantly augmented compared to higher Reynolds
number flows. A detailed incompressible numerical study of a single stage axial-flow
turbine at a low Reynolds number is investigated with the use of multiple eddy-viscosity
turbulence models. The study includes epistemic uncertainty quantification as a form of
numerical error estimation. The numerical results show good qualitative and quantitative
agreement with experimental data. It was found that the shear stress transport (SST) k - ω turbulence model with rotation/curvature correction and inclusion of transition modeling
is most capable at predicting the mean velocity distribution, which is further enhanced
when the URANS formulation is employed. However, all the cases indicate a large
variation in the prediction of the root-mean-squared of the turbulent velocity fluctuations.