Influence of Wake Structure on Unsteady Flow in an LP Turbine Blade Passage

The effect of wake structures on the evolution of the boundary layer over the suction side of a high-lift low-pressure turbine is studied using large-eddy simulation (LES) for a Reynolds number Re = 7.8×104 (based on the axial chord and inlet velocity). The wake data of different characteristics (defined by the wake deficit and the small-scale motion) are extracted from a precursor LES of flow past a cylinder. This replaces a moving bar that generates wakes in front of a cascade. LES results illustrate that apart from the wake kinematics, the large pressure oscillations and rollup of the separated shear layer along the rear half of the suction surface depend on the length scale of the convective wake. The transition of this rolled-up shear layer is influenced by the wake turbulence and the small-scale motion.