  Flow and heat transfer in a compressor rotating disc cavity with axial
throughflow is investigated using wall-modelled large-eddy simulations (WMLES).
These are compared to measurements from recently published experiments and used
to investigate high Reynolds number effects. The simulations use an open-source
CFD solver with high parallel efficiency and employ the Boussinesq
approximation for centrifugal buoyancy. Kinetic energy effects (characterised
by Eckert number) are accounted for by scaling the thermal boundary conditions
from static temperature to rotary stagnation temperature. The WMLES shows very
encouraging agreement with experiments up to the highest Reynolds number
tested, $Re_\phi=3.0\times10^6$. A further simulation at $Re_\phi=10^7$ extends
the investigation to an operating condition more representative of aero engine
high pressure compressors. The results support the scaling of shroud heat
transfer found at lower $Re_\phi$, but disc heat transfer is higher than
expected from a simple extrapolation of lower $Re_\phi$ results. This is
associated with transition to turbulence in the disc Ekman layers and is
consistent with the boundary layer Reynolds numbers at this condition. The
introduction of swirl in the axial throughflow, as may occur at engine
conditions, could reduce the boundary layer Reynolds numbers and delay the
transition.
