The Role of the Centerbody Wake on the Precessing Vortex Core Dynamics of a Swirl Nozzle

Mukherjee, Arnab; Muthichur, Nishanth; More, Chaitali; Gupta, Saarthak; Hemchandra, Santosh

doi:10.1115/1.0003155v

Cited by 4 publications

(16 citation statements)

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“…Nonetheless, the results also indicate that, in most cases, surprisingly accurate estimates of the limit cycle oscillation frequency can be obtained using mean flow stability analysis, even when the growth rate is not small. Similar determinations have been reached for swirling jets in the turbulent regime by Oberleithner et al (2011), Tammisola & Juniper (2016) and Mukherjee et al (2021), in addition to the more formal demonstration mentioned above by Manoharan et al (2020). This outcome is particularly convenient for the interpretation of experimental data, where time averages are readily accessible.…”

Section: The Wall-jet Regimesupporting

confidence: 80%

Nonlinear dynamics of fully developed swirling jets

2021

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Section: The Wall-jet Regimesupporting

confidence: 80%

Nonlinear dynamics of fully developed swirling jets

2021

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“…For example, in the turbulent regime, Mukherjee et al. (2021) and Gupta et al. (2021) have both suggested that PVC oscillation amplitudes may be diminished by increasing the centrebody diameter in order to merge the bubble and wake recirculation zones.…”

Section: Resultsmentioning

confidence: 99%

“…It is interesting to compare the results described above with existing works in the annular swirling jet literature that have considered the influence of the centrebody diameter. For example, in the turbulent regime, Mukherjee et al (2021) and Gupta et al (2021) have both suggested that PVC oscillation amplitudes may be diminished by increasing the centrebody diameter in order to merge the bubble and wake recirculation zones. This is akin to shifting the operating regime from a D-to E-type solution in figure 7.…”

Section: Influence Of Centrebody Size On Vortex Breakdown and Precessionmentioning

confidence: 99%

“…2021 a ; Mukherjee et al. 2021) and weakly nonlinear (Manoharan et al. 2020) mean flow stability analysis techniques have explained the so-called ‘global modes’ that seem to underlie many of the observed coherent structures (Mezić 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Classical linear stability analyses of parallel swirling jets and wakes have also been performed (Loiseleux, Chomaz & Huerre 1998;Loiseleux, Delbende & Huerre 2000). In turbulent swirling jets, linear (Oberleithner et al 2011;Rukes, Paschereit & Oberleithner 2016;Tammisola & Juniper 2016;Vanierschot et al 2020;Douglas et al 2021a;Mukherjee et al 2021) and weakly nonlinear (Manoharan et al 2020) mean flow stability analysis techniques have explained the so-called 'global modes' that seem to underlie many of the observed coherent structures (Mezić 2013). While several existing mean flow stability studies do consider swirling annular jets, none of the existing studies resolves the parameter space with enough detail to provide a comprehensive description of swirling annular jet behaviours.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics and bifurcations of laminar annular swirling and non-swirling jets

2022

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This paper presents bifurcation analyses characterising the nonlinear dynamics of fully developed laminar annular jets with respect to the centrebody diameter ${ {d}}$ , Reynolds number ${ {Re}}$ , and swirl ratio ${ {S}}$ . Similar flows appear in numerous applications and feature a vibrant range of topological and dynamical characteristics associated with phenomena including shear layer separation and vortex breakdown. Our results begin by describing the non-monotonic evolution of the axisymmetric jet's steady topology under varying ${ {S}}$ . In accord with earlier reports, the jet progresses through a sequence of wake, breakdown and wall jet regimes in a qualitatively similar manner across a wide span of ${ {d}}$ and ${ {Re}}$ values. In the wake regime, the non-swirling jet bifurcates to a plane-symmetric, but not axisymmetric, steady flow pattern beyond a ${ {d}}$ -dependent critical ${ {Re}}$ value. With further increase in ${ {Re}}$ , the steady non-swirling jet destabilises subsequently via multiple distinct Hopf bifurcations. Introducing ${ {S}}>0$ to the jet also induces unsteadiness by twisting the singly azimuthally periodic ( $|m|=1$ ) asymmetric wake structure and causing it to precess periodically in time about the central axis. Intermediate swirl stabilises this unsteady dynamics and restores the jet's axisymmetry. This stabilising effect is then reversed in the breakdown regime at higher ${ {S}}$ , where a variety of different $|m|=1$ and $|m|=2$ instabilities bifurcate from the steady flow as ${ {S}}$ is increased. Several instances of hysteresis and subcritical behaviour are reported and discussed, including one that manifests precessing vortex core oscillations.

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Impact of precessing vortex core dynamics on the thermoacoustic instabilities in a swirl-stabilized combustor

et al. 2022

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Global instabilities in swirling flows can significantly alter the flame and flow dynamics of swirl-stabilized flames, such as those in modern gas turbine engines. In this study, we characterize the interaction between the precessing vortex core (PVC), which is the consequence of a global hydrodynamic instability, and thermoacoustic instabilities, which are the result of a coupling between combustor acoustics and the unsteady heat release rate. This study is performed using experimental data obtained from a model gas turbine combustor employing two concentric swirling nozzles of air, separated by a ring of fuel injectors, operating at five bar pressure. The flow split between the two streams is systematically varied to observe the impact of flow structure variation on the system dynamics at both non-reacting and reacting conditions. High-speed stereoscopic particle image velocimetry, OH planar laser-induced fluorescence and acetone planar laser-induced fluorescence are used to obtain information about the velocity fields, flame and fuel flow behaviour, respectively. Spectral proper orthogonal decomposition and a complex network analysis are used to identify and characterize the dominant oscillation mechanisms driving the system. In the non-reacting data, a PVC is present in most cases and the amplitude of the oscillation increases with increasing flow through the centre nozzle. In the reacting data, three dominant modes are seen: two thermoacoustic modes and the PVC. Our results show that in the cases where the frequency of the PVC overlaps with either of the thermoacoustic modes, the thermoacoustic modes are suppressed. The complex network analysis coupled with a weakly nonlinear theoretical analysis suggests the mechanisms by which this coupling and suppression of the thermoacoustic mode occur.

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The Role of the Centerbody Wake on the Precessing Vortex Core Dynamics of a Swirl Nozzle

Cited by 4 publications

References 0 publications

Nonlinear dynamics of fully developed swirling jets

Nonlinear dynamics of fully developed swirling jets

Dynamics and bifurcations of laminar annular swirling and non-swirling jets

Impact of precessing vortex core dynamics on the thermoacoustic instabilities in a swirl-stabilized combustor

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