Re-Ingestion of Upstream Egress in a 1.5-Stage Gas Turbine Rig

J.A. Scobie, F.P. Hualca, M. Patinios, C.M. Sangan, J.M. Owen, G.D. Lock

Research output: Chapter in Book/Report/Conference proceedingConference paper

Abstract

In gas turbines, rim seals are fitted at the periphery of stator and rotor discs to minimise the purge flow required to seal the wheel-space between the discs. Ingestion (or ingress) of hot mainstream gases through rim seals is a threat to the operating life and integrity of highly-stressed components, particularly in the first-stage turbine. Egress of sealing flow from the first-stage can be re-ingested in downstream stages. This paper presents experimental results using a 1.5-stage test facility designed to investigate ingress into the wheelspaces upstream and downstream of a rotor disc. Re-ingestion was quantified using measurements of CO2 concentration, with seeding injected into the upstream and downstream sealing flows. Here a theoretical mixing model has been developed from first principles and validated by the experimental measurements. For the first time, a method to quantify the mass fraction of the fluid carried over from upstream egress into downstream ingress has been presented and measured; it was shown that this fraction increased as the downstream sealing flow rate increased. The upstream purge was shown to not significantly disturb the fluid dynamics but only partially mixes with the annulus flow near the downstream seal, with the ingested fluid emanating from the boundary layer on the blade platform. From the analogy between heat and mass transfer, the measured massconcentration flux is equivalent to an enthalpy flux and this re-ingestion could significantly reduce the adverse effect of ingress in the downstream wheel-space. Radial traverses using a concentration probe in and around the rim seal clearances provide insight into the complex interaction between the egress, ingress and mainstream flows.
Original languageEnglish
Title of host publicationProceedings of the ASME Turbo Expo
Number of pages11
VolumeVolume 5B-2017
ISBN (Electronic)978-0-7918-5088-6
DOIs
Publication statusPublished - 2017
Externally publishedYes
EventASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition: GT 2017 - Charlotte, United States
Duration: 26 Jun 201730 Jun 2017

Conference

ConferenceASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition
CountryUnited States
CityCharlotte
Period26/06/1730/06/17

Keywords

  • Purge Flow Re-Ingestion
  • Rotor-Stator Cavities

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