Turbulence models assessment for large-scale tip vortices in an axial compressor rotor

Six turbulence models frequently used in compressor aerodynamics were employed in the detailed numerical investigations of a low-speed large-scale axial compressor rotor, for which the tip flows were measured in detail with stereoscopic particle image velocimetry, to assess the predictive capabilities of the turbulence models for large-scale vortices in the tip region of the rotor. The six turbulence models include: the mixing-lengthh model, the Spalart-Allmaras model, the standard k - ε model, the shear-stress transport k - ω model, the ν^2̄ model, and the Reynolds stress model. Their results were carefully discussed and compared with the measurements both on velocity fields and turbulence stresses. It was found that the Reynolds stress model is superior to the others in the prediction of the tip-leakage vortex at the design condition, whereas the standard k - ε model shows the best results in the prediction of the corner vortex at the near-stall condition. Although the simulation could predict the large-scale tip vortices well in the mean flowfield, the computed flow mechanism has large discrepancy with the reality.