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dc.contributor.author
Baumann, Michael
dc.date.accessioned
2017-08-25T08:11:10Z
dc.date.available
2017-06-10T15:50:16Z
dc.date.available
2017-08-25T08:11:10Z
dc.date.issued
2013
dc.identifier.uri
http://hdl.handle.net/20.500.11850/65599
dc.identifier.doi
10.3929/ethz-a-009761333
dc.description.abstract
Combustion chambers of gas turbines can be viewed as organ pipes in which acoustic pressure and velocity oscillations can be sustained. Thermoacoustic instabilities can occur due to thermoacoustic coupling between the flame and the pressure oscillations. Acoustic resonators such as Helmholtz dampers are commonly used to increase the acoustic dissipation and abate the severe pressure oscillations. Yet, it remains a challenging task to derive conditions which promote the potential coupling. In order to predict the damper performance, a theoretical model combining the combustion instability and the damper dynamics is derived by Nicolas Noiray and Bruno Schuermans [9] from ALSTOM Power. The model consists of two nonlinear coupled differential equations of second order. The first equation describes the acoustic pressure oscillation in the combustor of one particular acoustic mode. The linear growth rate is captured by a linear damping term, whereas the boundedness of the solutions are ensured by a nonlinear damping term. The second equation describes the acoustic velocity oscillation in the neck of the Helmholtz damper, which includes a non-smooth damping term. The acoustic absorption is maximized when the eigenfrequency of the damper is adjusted to the unstable mode of the combustor. This special case is referred to as the perfectly tuned model, which is a special case of the general model including static detuning. The objective of this project is the nonlinear analysis of these models. The stability of the equilibrium is determined by an eigenvalue analysis and the region of attraction is approximated with the use of Lyapunov techniques. Due to the nonlinearities present in the system, several periodic solutions exist, which are approximated using three different methods from nonlinear dynamics, which are the center manifold reduction, the method of multiple scales and the method of averaging. The bifurcation analysis of the perfectly tuned model shows a wider range of dynamics than expected. Additionally to a supercritical Hopf bifurcation, also fold bifurcations and a cusp catastrophe can occur. The bifurcation branches define a partition of the parameter space into four regions of which every region has a different number of limit sets. The model with static detuning shows a similar behaviour. The pressure in the combustion chamber and the acoustic velocity in the neck of the Helmholtz damper oscillate at the same frequency. Yet, which is in contrast to the perfectly tuned model, there exists a phase shift between the oscillations and the frequency of oscillation depends on the bifurcation parameter.
en_US
dc.language.iso
en
en_US
dc.publisher
Eidgenössische Technische Hochschule Zürich, Institute of Mechanical Systems IMES
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
COMBUSTION CHAMBERS (GAS TURBINES)
en_US
dc.subject
THERMISCHE SCHWINGUNGSERREGUNG (AKUSTIK)
en_US
dc.subject
KELVIN-HELMHOLTZ INSTABILITY (FLUID DYNAMICS)
en_US
dc.subject
DAMPING OF MECHANICAL OSCILLATIONS (ACOUSTICS)
en_US
dc.subject
KELVIN-HELMHOLTZ INSTABILITÄT (FLUIDDYNAMIK)
en_US
dc.subject
BRENNKAMMERN (GASTURBINEN)
en_US
dc.subject
DÄMPFUNG MECHANISCHER SCHWINGUNGEN (AKUSTIK)
en_US
dc.subject
THERMAL EXCITATION OF VIBRATIONS (ACOUSTICS)
en_US
dc.title
Stability Analysis of Thermoacoustic Coupling in Damper-Equipped Combustion Chambers Including Nonlinearities
en_US
dc.type
Master Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2013
ethz.size
107 p.
en_US
ethz.code.ddc
6 - Technology, medicine and applied sciences::620 - Engineering & allied operations
en_US
ethz.identifier.nebis
009761333
ethz.publication.place
Zürich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::01159 - Lehre Maschinenbau und Verfahrenstechnik::01157 - SR Maschineningenieurwiss.::01154 - MSc Maschineningenieurwissenschaften / MSc Mechanical Engineering
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02618 - Institut für Mechanische Systeme / Institute of Mechanical Systems
en_US
ethz.date.deposited
2017-06-10T15:52:34Z
ethz.source
ECOL
ethz.source
ECIT
ethz.identifier.importid
imp5936507f159ea17076
ethz.identifier.importid
imp59366b3bc849829312
ethz.ecolpid
eth:6834
ethz.ecitpid
pub:104507
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-18T19:59:12Z
ethz.rosetta.lastUpdated
2017-08-25T08:11:17Z
ethz.rosetta.versionExported
true
ethz.COinS
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