POD-based analysis of combustion images in optically accessible engines

Bizon, Katarzyna; Continillo, Gaetano; Mancaruso, Ezio; Merola, Simona Silvia; Vaglieco, Bianca Maria

doi:10.1016/j.combustflame.2009.12.013

Cited by 63 publications

(35 citation statements)

References 10 publications

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“…For POD on velocity fields, the basis functions are themselves velocity fields, and most of the structure in the measured velocity field can be captured by a linear combination of only a few basis functions. In this case, we use the snapshot approach, developed by Sirovich (1987), which is more convenient when the number of collected samples is smaller than the space discretization, according to Bizon et al (2010). The snapshot approach has been applied in engine flow research to extract coherent structures from a turbulent flow in an unbiased way by Druault et al (2005) and Roudnitzky et al (2006) and also for decomposition of soot luminosity during combustion by Bizon et al (2009).…”

Section: Proper Orthogonal Decompositionmentioning

confidence: 99%

Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

et al. 2012

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High-speed particle image velocimetry (HS-PIV) using hollow microspheres has been applied to characterize the flow in a heavy-duty diesel engine during and after fuel injection. The injection timings were varied in the range representing those used in premixed charge compression ignition (PCCI) regimes, and multiple injections have been applied to investigate their influence on the flow inside the combustion chamber. By injecting into pure nitrogen, combustion is avoided and the flow can be studied long after injection. The results show a sudden change of air motion at the start of injection as a result of the air entrainment at the core of the spray. Furthermore, as expected, spray injection causes a considerable increase in the cycle-to-cycle fluctuations of the flow pattern, the more so for longer injection durations.

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Section: Proper Orthogonal Decompositionmentioning

confidence: 99%

Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

et al. 2012

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“…The essential idea of the POD is finding among a set of realizations of the flow fields the one that maximizes the mean square energy. The method has been intensively investigated for real-time flow control and physical process simulation because of its ability to yield a basis for low-order dynamic systems (Berkooz 1991;Ly and Tran 2001;Utturkar et al 2005;Rowley et al 2004;Ravindran 2002;Epureanu 2003;Perret et al 2006), and especially for the cyclic variability evaluation via statistical properties of the POD temporal coefficients (Druault et al 2005;Druault and Chaillou 2007;Roudnitzky et al 2006;Cosadia et al 2006;Bizon et al 2010;Fogleman et al 2004;Graftieaux et al 2001). The paper is organized as follows.…”

Section: Abbreviationsmentioning

confidence: 99%

Proper orthogonal decomposition analysis for cycle-to-cycle variations of engine flow. Effect of a control device in an inlet pipe

Guibert

2012

Exp Fluids

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This paper aims to investigate cycle-to-cycle variations of non-reacting flow inside a motored singlecylinder transparent engine in order to judge the insertion amplitude of a control device able to displace linearly inside the inlet pipe. Three positions corresponding to three insertion amplitudes are implemented to modify the main aerodynamic properties from one cycle to the next. Numerous particle image velocimetry (PIV) two-dimensional velocity fields following cycle database are posttreated to discriminate specific contributions of the fluctuating flow. We performed a multiple snapshot proper orthogonal decomposition (POD) in the tumble plane of a pent roof SI engine. The analytical process consists of a triple decomposition for each instantaneous velocity field into three distinctive parts named mean part, coherent part and turbulent part. The 3rd-and 4th-centered statistical moments of the proper orthogonal decomposition (POD)-filtered velocity field as well as the probability density function of the PIV realizations proved that the POD extracts different behaviors of the flow. Especially, the cyclic variability is assumed to be contained essentially in the coherent part. Thus, the cycle-to-cycle variations of the engine flows might be provided from the corresponding POD temporal coefficients. It has been shown that the in-cylinder aerodynamic dispersions can be adapted and monitored by controlling the insertion depth of the control instrument inside the inlet pipe.

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“…For example, Arienti et al (Arienti et al, 2008) used POD to investigate the dynamics of fluid jets. Bizon et al (Bizon et al, 2010) applied POD in internal combustion engines to investigate the scalar field of luminosity, thus receiving information about the flame dynamics.…”

Section: Proper Orthogonal Decompositionmentioning

confidence: 99%

“…The incoherent part should include all fluctuations for which no pattern can be identified over the burning process. It is commonly thought that the first few modes correspond to the average structure of the data, while higher order modes contain information about fluctuations (Bizon et al, 2010). The Nonlinear Iterative Partial Least Squares (NIPALS) algorithm is used for the principal component analysis in the POD method.…”

Section: Proper Orthogonal Decompositionmentioning

confidence: 99%

Evaluation techniques for optical analysis of hybrid rocket propulsion

Petrarolo

Kobald

2016

JFST

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This article summarizes recent results of data evaluation techniques obtained with optical investigations on the combustion behavior of hybrid rocket fuels. Tests are performed in a 2D slab burner configuration with windows on two sides. Liquefying paraffin-based fuels are tested in combination with gaseous oxygen (GOX). High speed videos of combustion tests are recorded in order to investigate the combustion phenomena of this kind of fuels. Hybrid combustion of liquefying fuels is dominated by transient flow dynamics like Kelvin-Helmholtz instability and vortex shedding, also due to the characteristic turbulent diffusion flame. In order to better evaluate these flow phenomena, characteristic frequencies and wavelengths of the main structures of the flow field and of the combustion flame appearing in the video data have to be found. In this work, a spatial and temporal analysis of these structures is carried out by using two different techniques, applied within an automated video evaluation routine. First of all, the Proper Orthogonal Decomposition (POD) technique is used. Its results deliver linearly uncorrelated variables, which are the principal components of the flow field. This method enables to recognize the main structures of the flow field and the combustion flame appearing in the video data. Secondly, the Independent Component Analysis (ICA) technique is applied to the same data. It is able to search for statistically independent, or as independent as possible, structures hidden in the data. It increases the independence to higher statistical orders with respect to POD. The basis functions found with the ICA are expected to describe the essential structure of the data and to resemble some physical processes involved in the combustion. With both methods it is possible to compute spatial and temporal coefficients, which can be later analyzed by applying a Power Spectral Density (PSD) in order to obtain the excited frequencies and wavelengths during the combustion. Finally, the results of the two methods are compared in order to better understand and interpret them. The results collected so far and the comparison of both techniques show that their application is consistent and useful for the automated evaluation of combustion data. Petrarolo and Kobald, Journal of Fluid Science and Technology, Vol.11, No.4 (2016) fuel grains for high thrust applications. The multiport design increases the residual mass of unburnt fuel and thereby decreases the delivered specific impulse. Instabilities are also more likely with this type of design.Liquefying hybrid rocket fuels were only found recently. Cryogenic solid n-pentane showed regression rates 5-10 times higher than polymeric hybrid fuels (Carrick and Larson, 1995, Larson et al., 1996, DeRose et al., 1997.Paraffin-based fuels, tested at Stanford University, show a 3-5 times higher regression rate at similar mass fluxes compared to polymers , Karabeyoglu, 1998. This is achieved by a different combustion mechanism. Paraffin fuels form a liquid layer on the...

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POD-based analysis of combustion images in optically accessible engines

Cited by 63 publications

References 10 publications

Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

Proper orthogonal decomposition analysis for cycle-to-cycle variations of engine flow. Effect of a control device in an inlet pipe

Evaluation techniques for optical analysis of hybrid rocket propulsion

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