Numerical simulation of turbulent flows in 3D decelerating cascades using Second Moment closure modeling

Analysis of turbulent flows in a 3D turbomachinery test-case has been carried out by using the accurate, fully validated low-Reynolds second-moment closure (SMC) of Hanjalic and Jakirlic (1998) coupled with a parallel stabilized finite element code. The adopted SMC, with DNS-based topology-free low-Re-number and near-wall modification implemented in the basic high-Renumber SMC, has been shown to reproduce well a range of wall-bounded turbulent flows, thus seeming promising for predicting complex turbomachinery flows (Borello et al., 2004). A preliminary assessment of the model functionality in the finite-element code, conducted in a flat plate transition flow showed very good agreement with experiments and LES results. Then, the turbulent flow in a 3D linear compressor cascade has been simulated. This test-case represents a severe challenge for turbulence models due to the presence of several loss mechanisms related to secondary flows. The predictions have shown a good level of accuracy in predicting all major phenomenological features and mean flow parameters of turbomachinery flows.