EXPERIMENTAL MEASUREMENTS OF BUOYANCY INDUCED FLOW IN ROTATING CAVITIES UNDER HIGH REYNOLDS NUMBER CONDITIONS

The buoyancy-induced flow structure and heat transfer in rotating cavities is a well-known conjugate problem. The disc temperatures affect the flow and vice versa. This creates a challenging environment to study as it is: three-dimensional, unstable, and unsteady. Further, the vast timescale range between the flow and thermal transients on the discs prove impractical to simulate within rapid engine design cycles, requiring validated reduced-order physics-based models. Literature has established the relationship between the temperature of the core and heat transfer and how this is affected by compressibility, resulting in a critical Reynolds Number at which disc Nusselt number is maximum. This work presents new thermal measurements of a rotating cavity at engine representative conditions under elevated test section absolute pressure from the Sussex Multiple Cavity Rig. The axial throughflow temperature rise is recorded by shaft mounted thermocouple rakes, offering the opportunity for first-order energy balance estimates. By increasing the density of the throughflow air, this allows the investigation at Re. and Gr rarely published from academic facilities, providing further in-sights into the interplay between the governing non-dimensional parameters. The results have shown, for all comparable cases of constant Ro, increasing Re. has reduced disc surface temperatures. Despite elevated Gr >= 10(13) and high temperature gradients, there is no conclusive evidence of thermal stratification and the associated sharp reduction in shroud heat transfer.