Advanced computational methods in identification of thermo-acoustic systems [Elektronische Ressource] / Krzysztof Kostrzewa. Betreuer: Manfred Aigner

Livia Nye Simpson-Poffenbarger

Informations

• Publié par: universitat_stuttgart
• Publié le: 01 janvier 2011
• Nombre de lectures: 29
• Langue: English
• Poids de l'ouvrage: 9 Mo

Extrait

1

Advanced computational methods in
identification of thermo-acoustic
systems



A thesis accepted by the Faculty of Aerospace Engineering and Geodesy of the
Universität Stuttgart in partial fulfilment of the requirements for the degree of
Doctor of Engineering Sciences (Dr.-Ing.)


by

Dipl.-Ing. Krzysztof Kostrzewa

born in Poznan


Main referee: Prof. Dr.-Ing. Manfred Aigner
Co-referee: Prof. Dr.-Ing. Franz Joos
thDate of defence: 17 Dezember 2010



Institute of Combustion Technology for Aerospace Engineering
University of Stuttgart
2011
II







































3




Acknowledgments



This thesis emerged from the studies I conducted during my employment with the Institute of
Combustion Technology (VT) at DLR in Stuttgart between 2003 and 2007. It is the result of an applied
research, which had many contributors to its success.
First of all, I would like to acknowledge the support and help of numerous people, without whom this
thesis would not have been ever possible:
My warmest thanks to Siemens AG from Mülheim an der Ruhr and DLR from Stuttgart for providing
the funding and equipment to undertake this project. Especially I would like to mention here Dr. -Ing.
Michael Huth and Dr. -Ing. Werner Krebs from Siemens AG, Prof. Dr. -Ing. Manfred Aigner and Dr. -Ing.
habil. Berthold Noll from DLR who provided invaluable information and advices, which helped steer the
project in a direction leading to its successful conclusion.
Furthermore, I would like to thank to my supervisors: Dr. -Ing. Joachim Lepers, Dr. -Ing. Sven Bethke
and Dipl. -Ing. Peter Kaufmann from Siemens with whom I was honored to work. Their positive attitudes
and useful advises kept the project moving forward even when the outlook seemed grim. I appreciate
their personal character and expertise that provided the insight to overcome the many issues
encountered in this project.
Thanks also to Prof. Wolfgang Polifke and Dr. -Ing. Andreas Huber from TU München for all their
advices and assistance with regard to system identification. I also highly appreciate the possibility to
work with the Acoustic Postprocessor developed at TU München.
Many thanks go out to all persons I have had the privilege of getting to know during my time at DLR
and Siemens. Especially, I would like to thank Dipl. -Ing. Axel Widenhorn from DLR for his great
assistance during this project. He was an invaluable source for almost any questions regarding acoustic
boundary conditions.
Finally, I would like to thank my entire family. My parents and wife have always supported my
endeavors. They have been always a great source of my motivations and inspirations. Through often-
difficult situations, my wife provided me a good home environment and an understanding for me.







4


































4 i




Contents



LIST OF FIGURES .............................................................................................................. V
LIST OF TABLES ............................................................................................................. XIII
NOMENCLATURE.............................................................................................................XV
ZUSAMMENFASSUNG ....................................................................................................XXI
SUMMARY .....................................................................................................................XXIII
1 INTRODUCTION.............................................................................................................1
1.1 RESEARCH OBJECTIVE ...................................................................................................... 4
1.2 LITERATURE OVERVIEW..................................................................................................... 5
1.3 THESIS OUTLINE.................................................................................................................. 7
2 THERMO-ACOUSTICALLY INDUCED COMBUSTION INSTABILITIES......................11
2.1 MECHANISM OF COMBUSTION INSTABILITIES.............................................................. 11
2.1.1 Rayleigh’s Criterion .................................................................................................................. 12
2.2 THERMO-ACOUSTIC INSTABILITIES SOLUTIONS METHOD ......................................... 13
2.2.1 Passive means......................................................................................................................... 13
2.2.2 Active means............................................................................................................................ 14
3 ACOUSTIC MODELING ...............................................................................................15
3.1 THEORY AND BASIC CONCEPTS..................................................................................... 15
3.1.1 Wave equation ......................................................................................................................... 15
3.1.2 Validity of linearity assumptions in thermo-acoustics ............................................................... 18
3.1.3 Solution methods ..................................................................................................................... 19
3.1.3.1 One-dimensional acoustic wave propagation.................................................................... 19
3.1.3.2 Acoustic damping.............................................................................................................. 21
3.1.3.3 Acoustic Impedance.......................................................................................................... 23
3.2 ONE-DIMENSIONAL ACOUSTIC NETWORK MODELS .................................................... 24
3.2.1 Transfer matrix method ............................................................................................................ 25
3.2.1.1 Straight duct element ........................................................................................................ 26

i ii Contents

3.2.1.4 Feedback mechanism in combustion systems.................................................................. 30
3.2.1.5 Characterization of acoustic stability................................................................................. 32
3.2.1.6 Limitation of the one-dimensional acoustic network codes ............................................... 34
4 MODELING OF TURBULENT REACTIVE AND NON-REACTIVE FLOWS
USING CFD ..................................................................................................................37
4.1 THEORY AND NUMERICAL MODELING OF TURBULENCE............................................ 37
4.1.1 Numerical simulation of turbulence .......................................................................................... 38
4.1.2 RANS modeling........................................................................................................................ 39
4.1.2.1 Classical turbulence models for unclosed terms ............................................................... 41
4.1.3 Unsteady RANS modeling........................................................................................................ 43
4.1.3.1 CFL requirement ............................................................................................................... 44
4.2 COMBUSTION MODELING................................................................................................. 45
4.2.1 Turbulent premixed flames....................................................................................................... 46
4.2.2 Combustion models.................................................................................................................. 47
5 NUMERICAL SYSTEM IDENTIFICATION OF THERMO-ACOUSTIC ELEMENTS ......51
5.1 FUNDAMENTALS OF NUMERICAL SYSTEM IDENTIFICATION...................................... 51
5.1.1 Characterization of discrete time systems................................................................................ 52
5.1.2 Linear Time Invariant (LTI) Systems ........................................................................................ 53
5.1.3 Frequency response of LTI systems ........................................................................................ 54
5.1.3.1 z-Transformation............................................................................................................... 54
5.1.3.2 Inverse z-Transformation .................................................................................................. 55
5.2 MODELS OF LTI SYS