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Aerospace 2018, 5(1), 12; https://doi.org/10.3390/aerospace5010012

Numerical Investigation on Windback Seals Used in Aero Engines

1
MTU Aero Engines AG, Dachauer Strasse 665, 80995 Munich, Germany
2
Laboratory of Fluid Mechanics & Turbomachinery, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
*
Author to whom correspondence should be addressed.
Received: 16 November 2017 / Revised: 4 January 2018 / Accepted: 12 January 2018 / Published: 20 January 2018
(This article belongs to the Special Issue Secondary Air Systems in Gas Turbine Engines)
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Abstract

Seals are considered one of the most important flow elements in turbomachinery applications. The most traditional and widely known seal is the labyrinth seal but in recent years other types like the brush or carbon seals were introduced since they considerably reduce the sealing air consumption. When seals are used for sealing of aero engine bearing chambers they are subjected to high “bombardment” through oil particles which are present in the bearing chamber. These particles mainly result from the bearings as a consequence of the high rotational speeds. Particularly when carbon or brush seals are used, problems with carbon formation (coking) may arise when oil gets trapped in the very tight gap of these seals. In order to prevent oil migration into the turbomachinery, particularly when the pressure difference over a seal is small or even negligible, significant improvement can be achieved through the introduction of so called windback seals. This seal has a row of static helical teeth (thread) and below this thread a scalloped or smooth shaft section is rotating. Depending on the application, a windback seal can be used alone or as a combination with another seal (carbon, brush or labyrinth seal). A CFD analysis carried out with ANSYS CFX version 11 is presented in this paper with the aim to investigate this seal type. The simulations were performed by assuming a two-phase flow of air and oil in the bearing compartment. Design parameters like seal clearance, thread size, scallop width, were investigated at different operating conditions. View Full-Text
Keywords: secondary air system; bearing chamber; windback seal; labyrinth seal; CFD; two phase flow secondary air system; bearing chamber; windback seal; labyrinth seal; CFD; two phase flow
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Flouros, M.; Cottier, F.; Hirschmann, M.; Salpingidou, C. Numerical Investigation on Windback Seals Used in Aero Engines. Aerospace 2018, 5, 12.

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