Simultaneous 5 kHz OH-PLIF/PIV for the study of turbulent combustion at engine conditions

Slabaugh, Carson D.; Pratt, Andrew C.; Lucht, Robert P.

doi:10.1007/s00340-014-5960-5

Cited by 42 publications

(21 citation statements)

References 43 publications

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“…The majority of existing approaches for detecting the flame front in an image are based either on direct binarization (Kiefer et al 2008;Haq et al 2002) or on local intensity gradients (Slabaugh et al 2015;Bayley et al 2012). When direct binarization is applied, an intensity threshold filter is used delivering a binary image containing areas of zeroes and ones, representing unburnt and burnt regions.…”

Section: Arxiv:151103753v2 [Cscv] 3 Feb 2016mentioning

confidence: 99%

“…Subsequently, the remaining flame front data points can be fitted with a mathematical function, from which parameters such as curvature and flame surface density can be derived eventually. Pre-processing the original images with filters for noise reduction and contour enhancement may be required in order to improve the clearness and robustness of the flame front detection (Slabaugh et al 2015;Sweeney and Hochgreb 2009;Malm et al 2000). However, when the signal-to-noise ratio is low or the edge to be detected is not sufficiently steep, the common data processing algorithms may reach their limits.…”

Section: Arxiv:151103753v2 [Cscv] 3 Feb 2016mentioning

confidence: 99%

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Shearlet-based detection of flame fronts

2016

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Identifying and characterizing flame fronts is the most common task in the computer-assisted analysis of data obtained from imaging techniques such as planar laser-induced fluorescence (PLIF), laser Rayleigh scattering (LRS), or particle imaging velocimetry (PIV). We present Complex Shearlet-Based Ridge and Edge Measure (CoShREM), a novel edge and ridge (line) detection algorithm based on complexvalued wavelet-like analyzing functions -so-called complex shearlets -displaying several traits useful for the extraction of flame fronts. In addition to providing a unified approach to the detection of edges and ridges, our method inherently yields estimates of local tangent orientations and local curvatures. To examine the applicability for high-frequency recordings of combustion processes, the algorithm is applied to mock images distorted with varying degrees of noise and real-world PLIF images of both OH and CH radicals. Furthermore, we compare the performance of the newly proposed complex shearlet-based measure to well-established edge and ridge detection techniques such as the Canny edge detector, another shearlet-based edge detector, and the phase congruency measure.

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Section: Arxiv:151103753v2 [Cscv] 3 Feb 2016mentioning

confidence: 99%

Section: Arxiv:151103753v2 [Cscv] 3 Feb 2016mentioning

confidence: 99%

Shearlet-based detection of flame fronts

2016

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“…Researchers have reported temporally resolved particle image velocimetry (PIV) coupled with planar laser-induced fluorescence of the OH radical (OH-PLIF) to visualize flow-flame interactions in complex flows. These techniques can be used to track transient events occurring in turbulent flames and have contributed significantly in understanding the underlying physics of flow-flame interaction [15] [16] [17]. Some of the recent experimental studies on RJICF reported in the literature have focused on understanding the associated velocity field and the flame structure at crossflow Reynolds number ranging from 1000 -50000 [18] [19] [20] [21] [22].…”

Section: Equationmentioning

confidence: 99%

“…The two-point correlation function has been used in highly turbulent and nonhomogenous flow fields, such as swirling flows, free shear jet flows, temporally evolving wakes etc., to compute the integral length scales [17][27] [28]. A self-similar two-point correlation profile implies that the turbulent processes producing and dissipating energy at different length scales are in equilibrium as 24 the flow evolves.…”

Section: Integral Length Scalesmentioning

confidence: 99%

High-repetition-rate planar measurements in the wake of a reacting jet injected into a swirling vitiated crossflow

Panda¹,

Roa

Slabaugh³

et al. 2016

Combustion and Flame

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Staged combustion has been explored for power generation gas turbine engines to increase engine efficiency with minimal contribution to pollutant formation. Secondary fuel injection into the vitiated flow from the primary combustion process is one approach. In this work, advanced diagnostic measurements were performed on an experimental representation of such a system, with a transverse jet injection into a swirling vitiated crossflow.High-repetition-rate simultaneous particle image velocimetry (PIV) and OH planar laser-induced fluorescence (PLIF) were performed at three measurement planes perpendicular to the jet axis. The measurements provided qualitative as well as quantitative information on the evolution of complex flow structures and transient events such as re-ignition, local extinction and vortex-flame interactions in the turbulent reacting flow. Transverse jets composed of H 2 mixed with N 2 and premixed natural gas and air were injected through a tube protruding into the crossflow. The vitiated crossflow is produced by a low swirl burner (LSB). The crossflow exhibits considerable swirl at the location of the transverse jet injection. Two momentum flux ratios, J=3 and J=8 were employed to study the effect of momentum flux ratio on the stabilization of reaction fronts. The time-averaged flow field show a pair of steady wake vortices, which were found to be much larger for J = 8 than for the J=3 case. The region with the maximum time-averaged OH-PLIF intensity was found to be localized between the wake vortex pairs. The wake Strouhal number was found to be invariant with respect to the momentum flux ratio. Based on the experimental data, it is hypothesized that the shear layer and wake field vortices play a significant role in stabilizing a steady reaction front within the near-wake region of the jet.

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“…fluorescence, which is a measure of the population density of the target species (15). By forming the exciting laser beam into a sheet, a strong feature of easily imaging the 2D fluorescence intensity in the plane of the sheet makes LIF one of the most popular method, named as planar laser induced fluorescence (PLIF), for combustion diagnosis (25). By rapidly scanning a laser sheet across a flow field of interest, 3D LIF have been realized and applied to image droplet combustion and propellant combustion (26).…”

Section: Introductionmentioning

confidence: 99%

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

Liu

2018

Applied Spectroscopy Reviews

148

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Laser absorption spectroscopy (LAS) has been rapidly developed and widely applied to combustion diagnosis in recent decades. As a costeffective tool for measuring multiple combustion parameters, LAS provides unique properties in terms of accuracy and sensitivity for understanding the reactions and kinetics in reactive flows. Line-ofsight and tomographic LAS techniques have stimulated numerous applications and been proved to be robust for in situ combustion diagnosis in uniform and non-uniform combustion fields, respectively. This review highlights the breakthroughs in the evolution of LAS techniques from the viewpoints of key principles, sensors and instrumentations developed for combustion diagnosis, with particular emphasis on a series of spatially-resolved LAS techniques with their recent applications on obtaining high-fidelity measurement results with minimal intrusion to the practical combustors. Along the way, we note some challenges and requirements for further development of the LAS-based combustion diagnosis.

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Simultaneous 5 kHz OH-PLIF/PIV for the study of turbulent combustion at engine conditions

Cited by 42 publications

References 43 publications

Shearlet-based detection of flame fronts

Shearlet-based detection of flame fronts

High-repetition-rate planar measurements in the wake of a reacting jet injected into a swirling vitiated crossflow

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

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