Flow Structures Inside a Rotor‐Stator Cavity

Abstract

This paper describes an experimental investigation initiated to determine the threedimensional flow field inside the rim seal cavity of a double‐shrouded rotor‐stator system. Thereby, the effects caused by perturbances in the rotor wall were additionally examined. The objective of this work is to provide detailed information about the mechanisms that can promote elevated temperature levels in the high pressure section of a gas turbine. Both ingested hot gas and windage heating generated at the rotor‐stator interface can severely affect the material temperatures and thus considerably increase the thermal load of the rotating parts. The flow velocities were measured by means of an advanced LDV system capable of providing phase‐resolved data. The flow field was determined for two different rotorstator combinations. One of the rotor disks contained small rectangular cavities, located at the disk rim and arranged uniformly in’ the circumferential direction. These elements are referred to as the shank cavities of the rotor disk. The mechanical torque was measured to demonstrate the influence of these elements on the windage power. The measurements were performed at operating conditions that are typical for aero‐engines. It is shown that a perturbed rotor surface can raise the drag notably. The experiments were conducted in a high speed test rig at rotational Reynolds numbers up to Re ϕ ≈ 4.2*10 6 . The data were plotted as the dimensionless moment coefficient c M and correlated with Re ϕ and the dimensionless cooling flow rate c w .