Proper Orthogonal Decomposition for Experimental Investigation of Swirling Flame Instabilities

Iudiciani, Piero; Duwig, Christopher; Hosseini, Seyed Mohammad; Szász, Róbert-Zoltán; Fuchs, László; Gutmark, Ephraim; Lantz, Andreas; Collin, Robert; Aldén, Marcus

doi:10.2514/6.2010-584

Cited by 8 publications

(4 citation statements)

References 21 publications

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“…The black square represents the couple of values of the time coefficients for the considered reconstructed snapshot. The couple indeed carries information about the phase angle and the present data are analogous to phase-averaged quantities where the phase information is read from the scatter plot of the time coefficients a 1 -a 2 [32]. In the top left of Fig.…”

Section: Pod and Epod Reconstructions Of The Instantaneous Snapshotsmentioning

confidence: 98%

“…16), hence isolating the motions of interest. As pointed out in [32], the procedure is similar to a phase averaging procedure, locking the samples to the phase of the excitation.…”

Section: Pod and Epod Reconstructions Of The Instantaneous Snapshotsmentioning

confidence: 99%

“…Therefore, Proper Orthogonal Decomposition (POD) [30] is presently applied for the cases of interest and enables to highlight large coherent structures (or at least a statistical representation of them) as set of relevant "modes". Such post-processing technique recently gained interest in combustion applications [14,23,[31][32][33]. It opens avenues for extracting information on the complex flow/flame dynamics and relevant response to the axial pulsation as presented in the following.…”

Section: Introductionmentioning

confidence: 99%

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Large Eddy Simulation of the Sensitivity of Vortex Breakdown and Flame Stabilisation to Axial Forcing

Iudiciani

Duwig

2011

Flow Turbulence Combust

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The effect of axial forcing on the flame/vortex breakdown interaction is studied, with particular focus on the Precessing Vortex Core (PVC). Large Eddy Simulation (LES), together with a filtered flamelet model describing the subgrid combustion, is performed to study a lean premixed flame undergoing mass flow fluctuations in a wide range of frequencies and amplitude. In average, forcing at frequencies lower than the PVC characteristic frequency moves the recirculation zone upstream the combustor in the premixing tube, while higher frequencies do not relevantly affect the flow/flame. With the help of Proper Orthogonal Decomposition (POD) a detailed analysis of the dynamics of the central recirculation zone (CRZ) is performed showing how the excitation at lower frequencies weakens the PVC and allows the flame to propagate upstream. Extended POD is also applied to illustrate the flow/flame interactions during the excitation cycle.

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Section: Pod and Epod Reconstructions Of The Instantaneous Snapshotsmentioning

confidence: 98%

“…16), hence isolating the motions of interest. As pointed out in [32], the procedure is similar to a phase averaging procedure, locking the samples to the phase of the excitation.…”

Section: Pod and Epod Reconstructions Of The Instantaneous Snapshotsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Large Eddy Simulation of the Sensitivity of Vortex Breakdown and Flame Stabilisation to Axial Forcing

Iudiciani

Duwig

2011

Flow Turbulence Combust

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“…This provides data that are more meaningful for increased understanding of turbulent flows in fluid mechanics or heat release distributions when imaging combustion chemiluminescence. POD was first applied to turbulent flows by Lumley and coworkers [30] but to date has been used to understand vorticity in swirl-stabilized combustors [31][32][33][34], periodic fluctuations in turbulent shear layers [35,36], vibrational modes in forced resonance systems [37], and fluctuations in V-gutter combustion wakes [38,39]. POD has also recently been used as a means to compare the large outputs from numerical simulations of large eddy simulations to experimental chemiluminescence data for validation purposes [40,41].…”

Section: Methodsmentioning

confidence: 99%

Multi-angular Flame Measurements and Analysis in a Supersonic Wind Tunnel Using Fiber-Based Endoscopes

Wickersham

et al. 2015

Journal of Engineering for Gas Turbines and Power

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This paper reports new measurements and analysis made in the Research Cell 19 supersonic wind-tunnel facility housed at the Air Force Research Laboratory. The measurements include planar chemiluminescence from multiple angular positions obtained using fiber-based endoscopes (FBEs) and the accompanying velocity fields obtained using particle image velocimetry (PIV). The measurements capture the flame dynamics from different angles (e.g., the top and both sides) simultaneously. The analysis of such data by proper orthogonal decomposition (POD) will also be reported. Nonintrusive and full-field imaging measurements provide a wealth of information for model validation and design optimization of propulsion systems. However, it is challenging to obtain such measurements due to various implementation difficulties such as optical access, thermal management, and equipment cost. This work therefore explores the application of the FBEs for nonintrusive imaging measurements in the supersonic propulsion systems. The FBEs used in this work are demonstrated to overcome many of the practical difficulties and significantly facilitate the measurements. The FBEs are bendable and have relatively small footprints (compared to high-speed cameras), which facilitates line-of-sight optical access. Also, the FBEs can tolerate higher temperatures than high-speed cameras, ameliorating the thermal management issues. Finally, the FBEs, after customization, can enable the capture of multiple images (e.g., images of the flow fields at multi-angles) onto the same camera chip, greatly reducing the equipment cost of the measurements. The multi-angle data sets, enabled by the FBEs as discussed above, were analyzed by POD to extract the dominating flame modes when examined from various angular positions. Similar analysis was performed on the accompanying PIV data to examine the corresponding modes of the flow fields. The POD analysis provides a quantitative measure of the dominating spatial modes of the flame and flow structures, and is an effective mathematical tool to extract key physics from large data sets as the high-speed measurements collected in this study. However, the past POD analysis has been limited to data obtained from one orientation only. The availability of data at multiple angles in this study is expected to provide further insights into the flame and flow structures in high-speed propulsion systems.

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Identification of coexisting dynamics in boundary layer flows through proper orthogonal decomposition with weighting matrices

et al. 2021

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A different version of the classic proper orthogonal decomposition (POD) procedure introducing spatial and temporal weighting matrices is proposed. Furthermore, a newly defined non-Euclidean (NE) inner product that retain similarities with the POD is introduced in the paper. The aim is to emphasize fluctuation events localized in spatio-temporal regions with low kinetic energy magnitude, which are not highlighted by the classic POD. The different variants proposed in this work are applied to numerical and experimental data, highlighting analogies and differences with respect to the classic and other normalized variants of POD available in the literature. The numerical test case provides a noise-free environment of the strongly organized vortex shedding behind a cylinder. Conversely, experimental data describing transitional boundary layers are used to test the capability of the procedures in strongly not uniform flows. By-pass and separated flow transition processes developing with high free-stream disturbances have been considered. In both cases streaky structures are expected to interact with other vortical structures (i.e. free-stream vortices in the by-pass case and Kelvin–Helmholtz rolls in the separated type) that carry a significant different amount of energy. Modes obtained by the non-Euclidean POD (NE-POD) procedure (where weighted projections are considered) are shown to better extract low energy events sparse in time and space with respect to modes extracted by other variants. Moreover, NE-POD modes are further decomposed as a combination of Fourier transforms of the related temporal coefficients and the normalized data ensemble to isolate the frequency content of each mode.

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Proper Orthogonal Decomposition for Experimental Investigation of Swirling Flame Instabilities

Cited by 8 publications

References 21 publications

Large Eddy Simulation of the Sensitivity of Vortex Breakdown and Flame Stabilisation to Axial Forcing

Large Eddy Simulation of the Sensitivity of Vortex Breakdown and Flame Stabilisation to Axial Forcing

Multi-angular Flame Measurements and Analysis in a Supersonic Wind Tunnel Using Fiber-Based Endoscopes

Identification of coexisting dynamics in boundary layer flows through proper orthogonal decomposition with weighting matrices

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