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A CFD-Based Prediction Method for Tip Clearance Losses and Deviations in Axial Turbines

Buske, Clemens (2020) A CFD-Based Prediction Method for Tip Clearance Losses and Deviations in Axial Turbines. In: ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition, GT 2020. ASME Turbo Expo 2020, 2020-09-21 - 2020-09-25, Virtual Conference. doi: 10.1115/GT2020-14645. ISBN 978-079188419-5.

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Accurate loss models are crucial for reliable turbine performance predictions using low-fidelity tools. However, the complex flow structure of the blade tip gap flow impedes an experimental deduction of a realistic tip clearance loss model. In this work, validated, high-fidelity CFD simulations are used to substitute the cost- and time-consuming experiments of a parameter study and to develop a modern, flexible and universal tip clearance model. The CFD model is based on a single stage high-pressure turbine. Inflow conditions and geometry of the rotor were specifically varied to separately study the effects of the significant parameters on the tip clearance loss and deviation. Partial correlations were formulated for each effect and combined to a new tip clearance model. Apart from commonly considered parameters such as gap height, blade loading and solidity, other parameters that are well known to have an effect but are still disregarded in most conventional loss correlations are also investigated, such as incidence, Reynolds number, rotor speed and boundary layer thickness. Furthermore, a downstream progression model is presented that reflects the local conditions of the incompletely mixed out wake flow. Interrelations between the effects are modeled by a Kriging surrogate model, which was refined by the space filling technique. The new model was validated by additional CFD simulations at unprobed operation conditions. In addition, the new model was implemented into a through flow method. Performance calculations were performed for a four-stage air turbine and compared with experimental data. In comparison with the conventional tip clearance correlations, the new model improves the performance predictions at all operation points.

Item URL in elib:https://elib.dlr.de/136575/
Document Type:Conference or Workshop Item (Speech)
Title:A CFD-Based Prediction Method for Tip Clearance Losses and Deviations in Axial Turbines
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Buske, ClemensUNSPECIFIEDhttps://orcid.org/0000-0003-4157-7415UNSPECIFIED
Date:September 2020
Journal or Publication Title:ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition, GT 2020
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:loss correlation, tip clearance, turbine
Event Title:ASME Turbo Expo 2020
Event Location:Virtual Conference
Event Type:international Conference
Event Start Date:21 September 2020
Event End Date:25 September 2020
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies (old), E - Gas Turbine (old)
Location: Göttingen
Institutes and Institutions:Institute of Propulsion Technology > Turbine
Deposited By: Grunwitz, Dr.-Ing. Clemens
Deposited On:10 Nov 2020 10:32
Last Modified:24 Apr 2024 20:38

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