FLOW AND HEAT TRANSFER IN A ROTATING DISC CAVITY WITH AXIAL THROUGHFLOW AT HIGH SPEED CONDITIONS

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 x 10(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.