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NUMERICAL SIMULATION OF MECHANICAL AND THERMAL FLUID–STRUCTURE INTERACTION IN LABYRINTH SEALS

Du, Yu (2010):
NUMERICAL SIMULATION OF MECHANICAL AND THERMAL FLUID–STRUCTURE INTERACTION IN LABYRINTH SEALS.
TU Darmstadt, [Online-Edition: urn:nbn:de:tuda-tuprints-22538],
[Ph.D. Thesis]

Abstract

Labyrinth seals are widely used in jet engines to control the air leakage and thus reduce the specific fuel consumption. The mechanical and thermal interaction of the leakage flow and the rotor/stator has strong influences on the performance of labyrinth seals. In previous numerical studies, such fluid–structure interaction (FSI) effects are usually treated by decoupling the fluid and solid fields. However, fully coupled FSI modeling is indeed required due to the tightly coupled physics. This thesis aims at investigating various mechanical and thermal FSI effects in labyrinth seals by means of numerical simulations. In particular, an implicit partitioned approach is applied to study the rotor vibration induced by fluid forces, the fluid–solid heat transfer, and the impact of centrifugal growth. The results show that, periodic oscillations of the rotor can be induced by fluid forces, and the amplitude is linearly dependent on the pressure ratio and mass flow. In the study of thermal and centrifugal effects, the difference between FSI and CFD simulations is discussed in depth, which provides guidelines on the choice of models for future research. Moreover, the influences of various operating conditions on the seal performance are thoroughly investigated in terms of primary dimensionless numbers. Finally, the heat transfer across the fluid–rotor/stator interfaces is discussed in detail. By introducing fully coupled FSI simulations, the current research of labyrinth seals is enriched in respect of: 1) studying FSI effects that are beyond the scope of individual CFD/CSM simulations; 2) reducing potential errors introduced by single field approximations; 3) obtaining additional information and more accurate predictions of fluid and solid fields.

Item Type: Ph.D. Thesis
Erschienen: 2010
Creators: Du, Yu
Title: NUMERICAL SIMULATION OF MECHANICAL AND THERMAL FLUID–STRUCTURE INTERACTION IN LABYRINTH SEALS
Language: English
Abstract:

Labyrinth seals are widely used in jet engines to control the air leakage and thus reduce the specific fuel consumption. The mechanical and thermal interaction of the leakage flow and the rotor/stator has strong influences on the performance of labyrinth seals. In previous numerical studies, such fluid–structure interaction (FSI) effects are usually treated by decoupling the fluid and solid fields. However, fully coupled FSI modeling is indeed required due to the tightly coupled physics. This thesis aims at investigating various mechanical and thermal FSI effects in labyrinth seals by means of numerical simulations. In particular, an implicit partitioned approach is applied to study the rotor vibration induced by fluid forces, the fluid–solid heat transfer, and the impact of centrifugal growth. The results show that, periodic oscillations of the rotor can be induced by fluid forces, and the amplitude is linearly dependent on the pressure ratio and mass flow. In the study of thermal and centrifugal effects, the difference between FSI and CFD simulations is discussed in depth, which provides guidelines on the choice of models for future research. Moreover, the influences of various operating conditions on the seal performance are thoroughly investigated in terms of primary dimensionless numbers. Finally, the heat transfer across the fluid–rotor/stator interfaces is discussed in detail. By introducing fully coupled FSI simulations, the current research of labyrinth seals is enriched in respect of: 1) studying FSI effects that are beyond the scope of individual CFD/CSM simulations; 2) reducing potential errors introduced by single field approximations; 3) obtaining additional information and more accurate predictions of fluid and solid fields.

Uncontrolled Keywords: Labyrinth seals, Fluid-Structure Interaction, fluid induced vibration, heat transfer, centrifugal effect, aircraft engines
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute of Numerical Methods in Mechanical Engineering (FNB)
Exzellenzinitiative
Exzellenzinitiative > Graduate Schools
Exzellenzinitiative > Graduate Schools > Graduate School of Computational Engineering (CE)
Zentrale Einrichtungen
Date Deposited: 06 Aug 2010 05:53
Official URL: urn:nbn:de:tuda-tuprints-22538
License: Creative Commons: Attribution-Noncommercial-No Derivative Works 3.0
Referees: Schäfer, Prof. Dr. Michael and Schiffer, Prof. Dr.- Heinz-Peter
Refereed / Verteidigung / mdl. Prüfung: 14 July 2010
Alternative Abstract:
Alternative abstract Language
Labyrinthdichtungen werden in Flugantrieben verwendet um den Leckageverlust zu kontrollieren und somit den spezifischen Brennstoffverbrauch zu reduzieren. Die mechanische und thermische Interaktion zwischen dem Fluid und dem Rotor/Stator hat einen starken Einfluss auf die Effizienz der Labyrinthdichtungen. In den bisherigen numerischen Untersuchungen wurde die Fluid–Struktur–Interaktion (FSI) normalerweise entkoppelt behandelt. Gekoppelte Modellierung ist allerdings notwendig aufgrund der interagierenden physikalischen Effekte. Ziel dieser Dissertation ist es die verschiedenen mechanischen und thermischen FSI–Effekte in Labyrinthdichtungen mittels numerischer Simulationen zu untersuchen. Ein implizites partitioniertes Verfahren wird verwendet um die Fluid–induzierte Rotorschwingung, den Fluid–Struktur–Wärmeübergang, und den zentrifugalen Effekt zu untersuchen. Die Ergebnisse zeigen, dass eine periodische Oszillation des Rotors durch die Strömung verursacht werden kann, wobei die Amplitude linear abhängig von dem Massenstrom und der Druckdifferenz ist. Bezüglich thermischer und zentrifugaler Effekte werden die FSI– und CFD–Simulationen verglichen, woraus eine Richtlinie für die Modellauswahl folgt. Außerdem werden die Einflüsse der Betriebsbedingungen auf die Leistung der Labyrinthdichtung anhand primären dimensionslosen Kennzahlen ausführlich diskutiert. Schließlich wird der Wärmeaustausch auf der Fluid–Struktur–Grenzfläche detailliert diskutiert. Die aktuelle Forschung der Labyrinthdichtungen wird durch die Einführung der FSI–Simulationen hinsichtlich folgender Punkte bereichert: 1) FSI–Effekte, die den Anwendungsbereich gewöhnlicher CFD/CSM–Analysen überschreiten, können simuliert werden; 2) Potenzielle Fehler aufgrund vereinfachenden Näherungen werden eliminiert; 3) Zusätzliche Informationen und genauere Voraussagen über das Verhalten des Fluids und der Struktur können erreicht werden.German
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