Large Eddy Simulation Investigation of Low Rossby Number Buoyant Flow in Rotating Cavities

Abstract

Flow and heat transfer in axial compressor disk cavities involve strong interaction of axial throughflow at the disk 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 modeled. 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 the dual cavity strong, unsteady interactions between the flows in the two cavities occur. These flow interactions result in less stable flow structures, higher air temperatures within the cavities and lower shroud and disk heat transfer compared to the single cavity case. FFT analysis reveals a complex phaselocking mechanism between flows in the two cavities.