| Popis: |
Flow and heat transfer in axial compressor disc cavities involve strong interaction of axial throughflow at the disc bores with centrifugal buoyant flow in the cavities. This paper presents large eddy simulation (LES) of flow and heat transfer in rotating cavities with a heated shroud and a relatively weak axial cooling throughflow. The conditions considered for a single cavity configuration correspond to Rossby numbers Ro = 0.2 and 0.3, rotational Reynolds numbers ReΩ = 3.2 × 105 and 7.7 × 105, and buoyancy parameters βΔT = 0.24 and 0.26. Reasonable agreement of the results with shroud heat transfer measurements was confirmed for the Ro = 0.2 condition for which test data were available. A dual cavity configuration for Ro = 0.3 and ReΩ = 3.2 × 105 is also modelled. The simulations show that, at low Ro conditions, flow reversals occur along the length of the bore flow path, upstream and downstream of the rotating cavities. With dual cavity this causes strong, unsteady interactions between the flows in the two cavities. These flow interactions result in less stable flow structures, higher air temperatures within the cavities and lower shroud and disc heat transfer compared to the single cavity case. FFT analysis reveals a complex phase-locking mechanism between flows in the two cavities. |
