Numerical Characterization of Hot Gas Ingestion through Turbine Rim Seals

Riccardo Da Soghe, Cosimo Bianchini, Carl Sangan, James Scobie, Gary Lock

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

Abstract

This paper deals with a numerical study aimed at the characterization
of hot gas ingestion through turbine rim seals. The
numerical campaign focused on an experimental facility which
models ingress through the rim seal into the upstream wheel-space
of an axial-turbine stage. Single-clearance arrangements
were considered in the form of axial- and radial-seal gap configurations.
With the radial-seal clearance configuration, CFD steady state
solutions were able to predict the system sealing effectiveness
over a wide range of coolant mass flow rates reasonably
well. The greater insight of flow field provided by the computations
illustrates the thermal buffering effect when ingress occurs:
for a given sealing flow rate, the effectiveness on the rotor
was significantly higher than that on the stator due to the axial
flow of hot gases from stator to rotor caused by pumping effects.
The predicted effectiveness on the rotor was compared with a
theoretical model for the thermal buffering effect showing good
agreement.
When the axial-seal clearance arrangement is considered,
the agreement between CFD and experiments worsens; the variation
of sealing effectiveness with coolant flow rate calculated by
means of the simulations display a distinct kink. It was found that
the ”kink phenomenon” can be ascribed to an over-estimation of
the egress spoiling effects due to turbulence modelling limitations.
Despite some weaknesses in the numerical predictions, the
paper shows that CFD can be used to characterize the sealing
performance of axial- and radial-clearance turbine rim seals.
LanguageEnglish
Title of host publicationProceedings of ASME Turbo Expo 2016
Place of PublicationSeoul, South Korea
PublisherASME
Number of pages12
Volume5A: Heat Transfer
ISBN (Print)978-0-7918-4978-1
DOIs
StatusPublished - 2016

Fingerprint

Seals
Turbines
Gases
Computational fluid dynamics
Rotors
Flow rate
Coolants
Thermal effects
Stators
Axial flow
Flow fields
Wheels
Turbulence
Experiments

Cite this

Da Soghe, R., Bianchini, C., Sangan, C., Scobie, J., & Lock, G. (2016). Numerical Characterization of Hot Gas Ingestion through Turbine Rim Seals. In Proceedings of ASME Turbo Expo 2016 (Vol. 5A: Heat Transfer). [GT2016-57421] Seoul, South Korea: ASME. https://doi.org/10.1115/GT2016-57421

Numerical Characterization of Hot Gas Ingestion through Turbine Rim Seals. / Da Soghe, Riccardo; Bianchini, Cosimo; Sangan, Carl; Scobie, James; Lock, Gary.

Proceedings of ASME Turbo Expo 2016. Vol. 5A: Heat Transfer Seoul, South Korea : ASME, 2016. GT2016-57421.

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

Da Soghe, R, Bianchini, C, Sangan, C, Scobie, J & Lock, G 2016, Numerical Characterization of Hot Gas Ingestion through Turbine Rim Seals. in Proceedings of ASME Turbo Expo 2016. vol. 5A: Heat Transfer, GT2016-57421, ASME, Seoul, South Korea. https://doi.org/10.1115/GT2016-57421
Da Soghe R, Bianchini C, Sangan C, Scobie J, Lock G. Numerical Characterization of Hot Gas Ingestion through Turbine Rim Seals. In Proceedings of ASME Turbo Expo 2016. Vol. 5A: Heat Transfer. Seoul, South Korea: ASME. 2016. GT2016-57421 https://doi.org/10.1115/GT2016-57421
Da Soghe, Riccardo ; Bianchini, Cosimo ; Sangan, Carl ; Scobie, James ; Lock, Gary. / Numerical Characterization of Hot Gas Ingestion through Turbine Rim Seals. Proceedings of ASME Turbo Expo 2016. Vol. 5A: Heat Transfer Seoul, South Korea : ASME, 2016.
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AB - This paper deals with a numerical study aimed at the characterizationof hot gas ingestion through turbine rim seals. Thenumerical campaign focused on an experimental facility whichmodels ingress through the rim seal into the upstream wheel-spaceof an axial-turbine stage. Single-clearance arrangementswere considered in the form of axial- and radial-seal gap configurations.With the radial-seal clearance configuration, CFD steady statesolutions were able to predict the system sealing effectivenessover a wide range of coolant mass flow rates reasonablywell. The greater insight of flow field provided by the computationsillustrates the thermal buffering effect when ingress occurs:for a given sealing flow rate, the effectiveness on the rotorwas significantly higher than that on the stator due to the axialflow of hot gases from stator to rotor caused by pumping effects.The predicted effectiveness on the rotor was compared with atheoretical model for the thermal buffering effect showing goodagreement.When the axial-seal clearance arrangement is considered,the agreement between CFD and experiments worsens; the variationof sealing effectiveness with coolant flow rate calculated bymeans of the simulations display a distinct kink. It was found thatthe ”kink phenomenon” can be ascribed to an over-estimation ofthe egress spoiling effects due to turbulence modelling limitations.Despite some weaknesses in the numerical predictions, thepaper shows that CFD can be used to characterize the sealingperformance of axial- and radial-clearance turbine rim seals.

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