  We present results of implicit large eddy simulation (LES) and different
Reynolds-averaged Navier-Stokes (RANS) models of the MTU 161 low pressure
turbine at an exit Reynolds number of 90,000 and exit Mach number of 0.6. The
LES results are based on a high order discontinuous Galerkin method and the
RANS is computed using a classical finite-volume approach. The paper discusses
the steps taken to create realistic inflow boundary conditions in terms of end
wall boundary layer thickness and free stream turbulence intensity. This is
achieved by tailoring the input distribution of total pressure and temperature,
Reynolds stresses and turbulent length scale to a Fourier series based
synthetic turbulence generator. With this procedure, excellent agreement with
the experiment can be achieved in terms of blade loading at midspan and wake
total pressure losses at midspan and over the channel height. Based on the
validated setup, we focus on the discussion of secondary flow structures
emerging due to the interaction of the incoming boundary layer and the turbine
blade and compare the LES to two commonly used RANS models. Since we are able
to create consistent setups for both LES and RANS, all discrepancies can be
directly attributed to physical modelling problems. We show that both a linear
eddy viscosity model and a differential Reynolds stress model coupled with a
state-of-the-art correlation-based transition model fail, in this case, to
predict the separation induced transition process around midspan. Moreover,
their prediction of secondary flow losses leaves room for improvement as shown
by a detailed discussion turbulence kinetic energy and anisotropy fields.
