Chemical species tomography of turbulent flows: Discrete ill-posed and rank deficient problems and the use of prior information

Daun, Kyle J.; Grauer, Samuel J.; Hadwin, Paul J.

doi:10.1016/j.jqsrt.2015.09.011

Cited by 87 publications

(49 citation statements)

References 36 publications

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“…The limited ray measurements b must be supplemented with a prior information by taking the physical attributes of the target field into consideration. Many reconstruction techniques incorporate a prior information (sample-based or temporal prior information) through the Bayesian formulation (137,156,157). In general, a prior information such as smoothness of the subject and non-negativity constraint can be combined with the incomplete data to improve the image quality (158).…”

Section: Tomographic Algorithmsmentioning

confidence: 99%

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

Liu

2018

Applied Spectroscopy Reviews

165

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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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Section: Tomographic Algorithmsmentioning

confidence: 99%

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

Liu

2018

Applied Spectroscopy Reviews

165

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“…The spectral density detected on the camera pixel corresponds to the sum (line-of-sight projection) of the light emitted along the light ray path through the probe volume. This is based on the fundamental radiative transfer equation (RTE), which relates the change in radiation intensity along a ray path to local absorption and volume emission [11,12]. In the CTC, the RTE is simplified by neglecting scattering and re-absorption.…”

Section: The Ctc Techniquementioning

confidence: 99%

3D Instantaneous Reconstruction of Turbulent Industrial Flames Using Computed Tomography of Chemiluminescence (CTC)

Unterberger

Röder

Giese

et al. 2018

Journal of Combustion

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Computed Tomography of Chemiluminescence (CTC) was used to reconstruct the instantaneous three-dimensional (3D) chemiluminescence field of a high-power industrial flame, which was made optically accessible, for the first time. The reconstruction used 24 projections that were measured simultaneously, in one plane and equiangularly spaced within a total fan angle of 172.5°. The 3D results were examined by plotting both vertical and horizontal slices, revealing highly wrinkled structures with good clarity. The results presented are one of a series of experimental demonstrations of CTC applications to turbulent gaseous flames. The work reveals the potential to use any kind of luminescence measurement, such as emission from heated particles in coal-fired flames, for analysis of the flame shape directly in 3D.

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“…In these conditions, we may assume a free turbulent jet model and simulate an ‘expected’ plume trajectory and velocity field at the measurement plane [ 19 , 11 ] or indeed adopt a more sophisticated fluid model if necessary [ 20 ]. In a recent study [ 7 ], the authors propose using a squared exponential prior that is consistent with turbulent flow mixing models while preserving the smoothness of the concentration profiles. The correlation between the magnitude of the velocity and the concentration of the particles in the plume hints for making a Gaussian assumption on the anticipated concentration profiles.…”

Section: Model-based Prior Informationmentioning

confidence: 99%

“…Such imaging problems are known to be ill-posed as they lack uniqueness, although a unique image can still be computed subject to enforcing some form of regularization. As discussed in some detail in [ 7 ], the choice of regularization is ultimately linked to whether the resulting inverse problem is discrete ill-posed or rank deficient. As the underlying attenuation model falls within the linear regime of the Beer–Lambert Law, the problem is well suited to the Tikhonov regularization [ 8 ], as well as iterative algorithms based on the Landweber iteration, exploiting their convergence properties in solving linear, ill-posed problems [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

An efficient approach for limited-data chemical species tomography and its error bounds

et al. 2016

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We present a computationally efficient reconstruction method for the limited-data chemical species tomography problem that incorporates projection of the unknown gas concentration function onto a low-dimensional subspace, and regularization using prior information obtained from a simple flow model. In this context, the contribution of this work is on the analysis of the projection-induced data errors and the calculation of bounds for the overall image error incorporating the impact of projection and regularization errors as well as measurement noise. As an extension to this methodology, we present a variant algorithm that preserves the positivity of the concentration image.

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Chemical species tomography of turbulent flows: Discrete ill-posed and rank deficient problems and the use of prior information

Cited by 87 publications

References 36 publications

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

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

3D Instantaneous Reconstruction of Turbulent Industrial Flames Using Computed Tomography of Chemiluminescence (CTC)

An efficient approach for limited-data chemical species tomography and its error bounds

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