Stability and Sensitivity Analysis of Hydrodynamic Instabilities in Industrial Swirled Injection Systems

Kaiser, Thomas Ludwig; Poinsot, Thiérry; Oberleithner, Kilian

doi:10.1115/1.4038283

Cited by 27 publications

(12 citation statements)

References 27 publications

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“…Based on experimental data, Paredes et al (2016) were able to reproduce the global mode shapes downstream of the mixing section of a combustor with global LSA. Tammisola & Juniper (2016) as well as Kaiser, Poinsot & Oberleithner (2018) followed in demonstrating the applicability and validity of global LSA on highly turbulent flows with a dominating PVC instability. Overall, the excellent match between global mean-flow eigenmodes and the PVC structure clearly confirms that the PVC is indeed the manifestation of a global mode, which can be very well determined from global and local stability analysis based on the mean of the fully turbulent flow.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, they showed that the receptivity to open-loop forcing reaches far upstream of the injector. Kaiser et al (2018) calculated the adjoint modes of the PVC in a more complex swirl injector geometry based on large-eddy simulations. Within their study, regions of high receptivity were also found inside the injector.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we address two central questions: firstly, we investigate where the PVC is most receptive to open-loop forcing within a fully turbulent flow. In contrast to previous work, we focus our attention on the flow region far upstream of the vortex breakdown bubble, which is expected to be most influential for the formation of the PVC, as indicated by previous studies (Kuhn et al 2016;Tammisola & Juniper 2016;Kaiser et al 2018;Lückoff et al 2018). Moreover, we validate the receptivity maps using active flow control, which directly leads to the second, more fundamental, question posed in this work: To what extent can the adjoint global mode based on the mean of a highly turbulent flow be used to guide and interpret flow control?…”

Section: Introductionmentioning

confidence: 99%

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Receptivity of the turbulent precessing vortex core: synchronization experiments and global adjoint linear stability analysis

et al. 2020

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The Precessing Vortex Core (PVC) is a coherent structure that can arise in swirling jets from a global instability. In this work, the PVC is investigated under highly turbulent conditions. The goal is to characterize the receptivity of the PVC to active flow control, both theoretically and experimentally. Based on stereoscopic particle image velocimetry and surface pressure measurements, the experimental studies are facilitated by Fourier decomposition and proper orthogonal decomposition. The frequency and the mode shape of the PVC are extracted and a very good agreement with the theoretical prediction by global linear stability analysis (LSA) is found. By employing an adjoint LSA, it is found that the PVC is particularly receptive inside the duct upstream of the swirling jet. Open-loop zero net mass flux actuation is applied at different axial positions inside the duct with the goal of frequency synchronization of the PVC. The actuation is shown to have the strongest effect close to the exit of the duct. There, frequency synchronization is reached primarily through direct mode-to-mode interaction. Applying the actuation farther upstream, synchronization is only achieved by a modification of the mean flow that manipulates the swirl number. These experimental observations match qualitatively well with the theoretical receptivity derived from adjoint LSA. Although the process of synchronization is very complex, it is concluded that adjoint LSA based on mean field theory sufficiently predicts regions of high and low receptivity. Furthermore, the adjoint framework promises to be a valuable tool for finding ideal locations for flow control applications.Key words: Authors should not enter keywords on the manuscript, as these must be chosen by the author during the online submission process and will then be added during the typesetting process (see http://journals.cambridge.org/data/relatedlink/jfmkeywords.pdf for the full list) †

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Receptivity of the turbulent precessing vortex core: synchronization experiments and global adjoint linear stability analysis

et al. 2020

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“…Recent studies have shown that this linear framework not only predicts the PVC quantitatively correct, but allows and determines the flow regions of its origin at reacting and non-reacting conditions. 1,[3][4][5][26][27][28][29][30][31][32] Moreover, the mean field stability analysis allows for the prediction of the receptivity of the global mode to open-loop actuation, which is of utmost importance for the current control approach. 28,29,33,34 This receptivity can be represented as a two-dimensional map revealing those regions of the flow where external periodic actuation has most influence on global modes.…”

Section: Introductionmentioning

confidence: 99%

“…28,32,34 This approach was applied to realistic swirling fuel injector flows that give rise to a PVC. 29,30 The authors showed that the receptivity of the helical PVC mode is highest upstream of the central recirculation zone on the jet centerline in the vicinity of the nozzle outlet and the centerbody.…”

Section: Introductionmentioning

confidence: 99%

Excitation of the precessing vortex core by active flow control to suppress thermoacoustic instabilities in swirl flames

Lückoff

Oberleithner

2019

International Journal of Spray and Combustion Dynamics

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In this study, we apply periodic flow excitation of the precessing vortex core at the centerbody of a swirl-stabilized combustor to investigate the impact of the precessing vortex core on flame shape, flame dynamics, and especially thermoacoustic instabilities. The current control scheme is based on results from linear stability theory that determine the precessing vortex core as a global hydrodynamic instability with its maximum receptivity to open-loop actuation located near the center of the combustor inlet. The control concept is first validated at isothermal conditions. This is of utmost importance for the proceeding studies that focus on the exclusive impact of the precessing vortex core on the combustion dynamics. Subsequently, the control is applied to reacting conditions considering lean premixed turbulent swirl flames. Considering thermoacoustically stable flames first, it is shown that the actuation locks onto the precessing vortex core when it is naturally present in the flame, which allows the precessing vortex core frequency to be controlled. Moreover, the control allows the precessing vortex core to be excited in conditions where it is naturally suppressed by the flame, which yields a very effective possibility to control the precessing vortex core amplitude. The control is then applied to thermoacoustically unstable conditions. Considering perfectly premixed flames first, it is shown that the precessing vortex core actuation has only a minor effect on the thermoacoustic oscillation amplitude. However, we observe a continuous increase of the thermoacoustic frequency with increasing precessing vortex core amplitude due to an upstream displacement of the mean flame and resulting reduction of the convective time delay. Considering partially premixed flames, the precessing vortex core actuation shows a dramatic reduction of the thermoacoustic oscillation amplitude. In consideration of the perfectly premixed cases, we suspect that this is caused by the precessing vortex core-enhanced mixing of equivalence ratio fluctuations at the flame root and due to a reduction of time delays due to mean flame displacement.

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Mean field coupling mechanisms explaining the impact of the precessing vortex core on the flame transfer function

Lückoff

Kaiser

Paschereit

et al. 2021

Combustion and Flame

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Stability and Sensitivity Analysis of Hydrodynamic Instabilities in Industrial Swirled Injection Systems

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 27 publications

References 27 publications

Receptivity of the turbulent precessing vortex core: synchronization experiments and global adjoint linear stability analysis

Receptivity of the turbulent precessing vortex core: synchronization experiments and global adjoint linear stability analysis

Excitation of the precessing vortex core by active flow control to suppress thermoacoustic instabilities in swirl flames

Mean field coupling mechanisms explaining the impact of the precessing vortex core on the flame transfer function

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