The boundary layer represents the thin layer between the wall and the free stream. Although this zone is small in respect to the free stream its state - whether it is laminar or turbulent - has a high impact on wall parameters like skin friction but also on the free stream. The state of the boundary layer is influenced by free stream parameters like free stream turbulence intensity or acceleration. Transition can occur from laminar to turbulent, but also from turbulent to laminar. The latter process is called relaminarization. Transition and relaminarization has already been detected in laboratory conditions but also occur in real-life flow around aeroplane wings, but also in turbomachines. In this work a high pressure stator of a two-spool, two-stage turbine is analyzed numerically regarding transition and relaminarization to show how the boundary layer flow along casing and blade is influenced by these phenomena. It is found out in this work, that the boundary layer along the blade, hub and shroud undergoes transition and also relaminarization despite the high free stream velocities and turbulence levels inside the machine. The differences between a transitional and fully turbulent simulation regarding loss generation by wall friction are given.
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