Vortex Tracking of Purge-Mainstream Interactions in a Rotating Turbine Stage

Abstract The use of purge flow in gas turbines allows for high turbine entry temperatures, which are essential to produce cycle efficiency. Purge air is bled from the compressor and reintroduced cool vulnerable components. Wheel-spaces formed between adjacent rotating stationary discs, with supplied at low radius before exiting into mainstream gas-path through a rim-seal disc periphery. An aerodynamic penalty incurred as egress interacts mainstream. This study presents unparalleled three-dimensional velocity data single-stage test rig, specifically designed investigate egress–mainstream interaction using optical measurement techniques. Volumetric velocimetry applied environment phase-locked measurements used identify track vortical secondary features blade passage. A baseline case without compared experiments 1.7% mass fraction; latter was chosen ensure fully sealed wheel-space. non-localized vortex tracking function position core centroids. strength vortices determined circulation criterion on rotated planes aligned filaments. pressure-side leg horseshoe second associated were identified by experimental campaign. In absence flow, two merged, forming passage (PV). With addition cores remained independent 40% axial chord, while also demonstrating an increased radial migration intensification PV. shown remain closer suction-surface flow. Importantly, where filaments demonstrated strong or tangential components velocity, level calculated underpredicted true up 50%.