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Tomographic and Volumetric Diagnostics in Flames

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (31 January 2021) | Viewed by 11132

Special Issue Editors


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Guest Editor
Institute for Combustion and Gas Dynamics (IVG), Fluid Dynamics, University of Duisburg-Essen, 47047 Duisburg, Germany
Interests: tomographic techniques in energy- and process-technology; flame tomography; evolutionary reconstruction techniques (ERT); background-oriented schlieren tomography; multi-simultaneous measurements

E-Mail Website
Guest Editor
Institute for Combustion and Gas Dynamics (IVG), Fluid Dynamics, University of Duisburg-Essen, 47047 Duisburg, Germany
Interests: flame tomography; large-eddy simulation of combustion; direct numerical simulation of flames; nano-particle synthesis; modelling

Special Issue Information

Dear Colleagues,

Stringent regulations concerning pollutant and greenhouse gas emissions, safety and cost concerns, and fuel load and stability issues all call for the need to improve combustion devices. This can only be achieved with an in-depth understanding of realistic flames, which, in most cases, are turbulent. A fundamental understanding of such flames, as well as advanced numerical simulations, require experimental data that should ideally be time-resolved and volumetric, due to the inherent unsteadiness and three-dimensionality of the flames.

With this Special Issue, we aim to present recent work on tomographic and volumetric imaging in flames. We advise that papers should not exceed 12 pages in length. Review papers are also welcome, but please contact us if you plan to prepare one.

Prof. Dr. Khadijeh Mohri
Prof. Dr.-Ing. Andreas M. Kempf
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

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Keywords

  • Flame tomography
  • Extracting quantitative information from flame reconstructions
  • Phantom study strategies for tomography algorithm development
  • Novel tomography algorithms
  • High accuracy camera calibration methods
  • Laser-based techniques
  • Light field imaging
  • Time-resolved data
  • High resolution data
  • Industrial applications
  • Thermo-acoustics applications
  • Methods for the analysis of volumetric data

Published Papers (4 papers)

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Research

19 pages, 4719 KiB  
Article
Two-Dimensional Tomographic Simultaneous Multispecies Visualization—Part II: Reconstruction Accuracy
by Thomas Häber, Rainer Suntz and Henning Bockhorn
Energies 2020, 13(9), 2368; https://doi.org/10.3390/en13092368 - 9 May 2020
Cited by 4 | Viewed by 1710
Abstract
Recently we demonstrated the simultaneous detection of the chemiluminescence of the radicals OH* (310 nm) and CH* (430 nm), as well as the thermal radiation of soot in laminar and turbulent methane/air diffusion flames. As expected, a strong spatial and temporal coupling of [...] Read more.
Recently we demonstrated the simultaneous detection of the chemiluminescence of the radicals OH* (310 nm) and CH* (430 nm), as well as the thermal radiation of soot in laminar and turbulent methane/air diffusion flames. As expected, a strong spatial and temporal coupling of OH* and CH* in laminar and moderate turbulent flames was observed. Taking advantage of this coupling, multispecies tomography enables us to quantify the reconstruction quality completely independent of any phantom studies by simply utilizing the reconstructed distribution of both species. This is especially important in turbulent flames, where it is difficult to separate measurement noise from turbulent fluctuations. It is shown that reconstruction methods based on Tikhonov regularization should be preferred over the widely used algebraic reconstruction technique (ART) and multiplicative algebraic reconstruction techniques (MART), especially for high-speed imaging or generally in the limit of low signal-to-noise ratio. Full article
(This article belongs to the Special Issue Tomographic and Volumetric Diagnostics in Flames)
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25 pages, 13928 KiB  
Article
Two-Dimensional Tomographic Simultaneous Multi-Species Visualization—Part I: Experimental Methodology and Application to Laminar and Turbulent Flames
by Thomas Häber, Henning Bockhorn and Rainer Suntz
Energies 2020, 13(9), 2335; https://doi.org/10.3390/en13092335 - 7 May 2020
Cited by 3 | Viewed by 2212
Abstract
In recent years, the tomographic visualization of laminar and turbulent flames has received much attention due to the possibility of observing combustion processes on-line and with high temporal resolution. In most cases, either the spectrally non-resolved flame luminescence or the chemiluminescence of a [...] Read more.
In recent years, the tomographic visualization of laminar and turbulent flames has received much attention due to the possibility of observing combustion processes on-line and with high temporal resolution. In most cases, either the spectrally non-resolved flame luminescence or the chemiluminescence of a single species is detected and used for the tomographic reconstruction. In this work, we present a novel 2D emission tomographic setup that allows for the simultaneous detection of multiple species (e.g., OH*, CH* and soot but not limited to these) using a single image intensified CCD camera. We demonstrate the simultaneous detection of OH* (310 nm), CH* (430 nm) and soot (750 nm) in laminar methane/air, as well as turbulent methane/air and ethylene/air diffusion flames. As expected, the reconstructed distributions of OH* and CH* in laminar and turbulent flames are highly correlated, which supports the feasibility of tomographic measurements on these kinds of flames and at timescales down to about 1 ms. In addition, the possibilities and limitations of the tomographic approach to distinguish between locally premixed, partially premixed and non-premixed conditions, based on evaluating the local intensity ratio of OH* and CH* is investigated. While the tomographic measurements allow a qualitative classification of the combustion conditions, a quantitative interpretation of instantaneous reconstructed intensities (single shot results) has a much greater uncertainty. Full article
(This article belongs to the Special Issue Tomographic and Volumetric Diagnostics in Flames)
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12 pages, 1566 KiB  
Article
Axisymmetric Linear Hyperspectral Absorption Spectroscopy and Residuum-Based Parameter Selection on a Counter Flow Burner
by Johannes Emmert, Martina Baroncelli, Sani v.d. Kley, Heinz Pitsch and Steven Wagner
Energies 2019, 12(14), 2786; https://doi.org/10.3390/en12142786 - 19 Jul 2019
Cited by 14 | Viewed by 2344
Abstract
Chemical species tomography enables non-invasive measurements of temperatures and concentrations in gas phase processes. In this work, we demonstrate the recently introduced linear hyperspectral absorption tomography (LHAT) on an axisymmetric counterflow burner used for speciation studies of Oxyfuel combustion. As LHAT reconstructs spectrally [...] Read more.
Chemical species tomography enables non-invasive measurements of temperatures and concentrations in gas phase processes. In this work, we demonstrate the recently introduced linear hyperspectral absorption tomography (LHAT) on an axisymmetric counterflow burner used for speciation studies of Oxyfuel combustion. As LHAT reconstructs spectrally resolved local absorption coefficient spectra, the physical plausibility of these reconstructed spectra degrades with an over-regularization of the tomographic problem. As presented in this work, this behavior can be employed in a novel regularization parameter choice method based on the residuals of local spectroscopic fits to the reconstructed spectra. After determining the regularization parameter, the reconstructions of the temperature and water mole fraction profiles of different flames are compared to numerical simulations, showing a good agreement. Full article
(This article belongs to the Special Issue Tomographic and Volumetric Diagnostics in Flames)
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20 pages, 3911 KiB  
Article
3D Evolutionary Reconstruction of Scalar Fields in the Gas-Phase
by Andreas Unterberger, Andreas Kempf and Khadijeh Mohri
Energies 2019, 12(11), 2075; https://doi.org/10.3390/en12112075 - 30 May 2019
Cited by 18 | Viewed by 4273
Abstract
An evolutionary reconstruction technique (ERT) was developed for three-dimensional (3D) reconstruction of luminescent objects, in particular turbulent flames for the first time. The computed tomography (CT) algorithm is comprised of a genetic algorithm (GA) and a ray-tracing software. To guide the reconstruction process, [...] Read more.
An evolutionary reconstruction technique (ERT) was developed for three-dimensional (3D) reconstruction of luminescent objects, in particular turbulent flames for the first time. The computed tomography (CT) algorithm is comprised of a genetic algorithm (GA) and a ray-tracing software. To guide the reconstruction process, a mask is introduced. It uses a Metropolis algorithm (MA) to sample locations where specific genetic operators can be applied. Based on an extensive parameter study, performed on several types of phantoms, the ability of our algorithm for 3D reconstructions of fields with varying complexities is demonstrated. Furthermore, it was applied to three experiments, to reconstruct the instantaneous chemiluminescence field of a bunsen flame, a highly turbulent swirl flame and the turbulent Cambridge-Sandia stratified flame. Additionally, we show direct and quantitative comparison to an advanced computed tomography of chemiluminescence (CTC) method that is based on an algebraic reconstruction technique (ART). The results showed good agreement between CTC and ERT using both phantom data from flame simulations, and experimental data. Full article
(This article belongs to the Special Issue Tomographic and Volumetric Diagnostics in Flames)
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