Prediction of ingestion through turbine rim seals part 1: rotationally-induced ingress

Research output: Chapter in Book/Report/Conference proceedingChapter

10 Citations (Scopus)

Abstract

The mainstream flow past the stationary nozzle guide vanes and rotating turbine blades in a gas turbine creates an unsteady non-axisymmetric variation of pressure in the annulus radially outward of the rim seal. Ingress and egress occur through those parts of the seal clearance where the external pressure is higher and lower, respectively, than that in the wheel-space; this non-axisymmetric type of ingestion is referred to here as externally-induced (EI) ingress. Another cause of ingress is that the rotating air inside the wheel-space creates a radial gradient of pressure so that the pressure inside the wheel-space can be less than that outside; this creates rotationally-induced (RI) ingress, which unlike El ingress - can occur even if the flow in the annulus is axisymmetric. Although El ingress is usually dominant in a turbine, there are conditions under which both El and RI ingress are significant: these cases are referred to as combined ingress.

In Part 1 of this two-part paper, the so-called orifice equations are derived for compressible and incompressible swirling flow, and the incompressible equations are solved analytically for RI ingress. The resulting algebraic expressions show how the nondimensional ingress and egress vary with Theta(0), the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. It is shown that epsilon, the sealing effectiveness, depends principally on Theta(0), and the predicted values of e are in mainly good agreement with available experimental data.

Part 2 (ASME GT2009-59122) concentrates on the solution and validation of the orifice equations for EI and combined ingress.

Original languageEnglish
Title of host publicationProceedings of the ASME Turbo Expo 2009
PublisherASME
Pages1071-1082
Number of pages12
Volume3
ISBN (Electronic)978-0-7918-3849-5
ISBN (Print)9780791848845
DOIs
Publication statusPublished - 2009
Event54th ASME Turbo Expo 2009: Power for Land, Sea, and Air - Orlando, USA United States
Duration: 8 Jun 200912 Jun 2009

Conference

Conference54th ASME Turbo Expo 2009
CountryUSA United States
CityOrlando
Period8/06/0912/06/09

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