Flow in a "cover-plate" preswirl rotor-stator system

This paper describes a combined theoretical, computational, and experimental study of the flow in an adiabatic preswirl rotor-stator system. Preswirl cooling air, supplied through nozzles in the stator, flows radially outward, in the rotating cavity between the rotating disk and a cover-plate attached to it, leaving the system through blade-cooling holes in the disk. An axisymmetric elliptic solver, incorporating the Launder-Sharma low-Reynolds-number k - epsilon turbulence model, is used to compute the flow. An LDA system is used to measure the tangential component of velocity, V-phi, in the rotating cavity of a purpose-built rotating-disc rig. For rotational Reynolds numbers up to 1.2 x 10(6) and preswirl ratios up to 2.5, agreement between the computed and measured values of V-phi is mainly very good, and the results confirm that free-vortex flow occurs in most of the rotating cavity. Computed values of the preswirl effectiveness (or the nondimensional temperature difference between the preswirl and blade-cooling air) agree closely with theoretical values obtained from a thermodynamic analysis of an adiabatic system.