Prediction of Tip-Leakage Flow in Axial Flow Compressor With Second Moment Closure

An innovative analysis based on second-moment closure (SMC), incorporating proper modelling of low-Re-number and wall proximity effects is adopted in conjunction with numerical model based on an in-house parallel finite element code for the prediction of a 3D linear compressor cascade flow with tip clearance. The strong interaction between the tip leakage vortex, the mainstream, the passage vortex and the other turbulent structures causes important portion of energy losses and it influences the overall performance of the compressors. A systematic comparison of the prediction of the proposed SMC with respect to a linear eddy viscosity closure (standard k-ε) and experiments is carried out. In the tip leakage the turbulent flow is characterized by an high level of anisotropy induced by complex shear effects. The present predictions demonstrates that second moment closures feature a superior capability to reproduce all major phenomenological features and mean flow parameters of turbomachinery flows.