A lot of studies on turbomachinery main flow optimisation have been performed in order
to reach actual efficiency level of modern gas turbines. To go further in the study of
aerodynamic losses sources, a better understanding on technological effects is required.
Tip shroud cavities in low pressure turbine is an example. Indeed, the by-pass flow causes
additional pressure losses. In addition, interactions between main flow and cavity flows,
as well as the re-entering flow, cause mixing losses and modifications of flow angle. This
paper investigates the contribution of tip shroud cavities in a low pressure turbine stage
on flow structures using (Unsteady) Reynolds Averaged Navier-Stokes simulations. The
ability of a steady simulation to predict the overall performance and flow physics of this
kind of flow is well documented in the literature but time-resolved simulations are needed
to deepen the analysis. This is an objective of this paper. Following the presentation of the
configuration under investigation, an analysis of flow structures is made in the upstream
region of the rotor, close to the shroud. After that, simulations at off-design conditions are
studied in order to evaluate this impact on the previous mechanisms
