Multi-parameter estimation for spatially-resolved measurement of two-component velocity using absorption tomography

Gamba, Mirko

doi:10.2514/6.2015-1222

Cited by 2 publications

(2 citation statements)

References 29 publications

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“…The line shift item in a voxel contains three unknowns, Finally, we discuss the influence of the Fourier transform on the method. In the proposed work [18] the author used the Fourier transform to change the mathematical formulation of the reconstruction problem. In practice, the absorbance profile is sampled only a finite number of times in the sampling sequence and the continuous Fourier transform is approximated by the discrete Fourier transform (DFT).…”

Section: Discussionmentioning

confidence: 99%

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Reconstruction of two-dimensional velocity distribution in scramjet by laser absorption spectroscopy tomography

Cao

et al. 2018

Appl. Opt.

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Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX We propose a method to reconstruct the two-dimensional (2D) velocity distribution of flow fields by laser absorption spectroscopy tomography. A mathematic model is established to reveal the dependence of spectral absorbance on line-of-sight velocity distribution. Then, with multiple laser beams from different angular views covering the region of interest, a nonlinear equation set of 2D velocity distribution is established according to the model. The integrated absorbance coefficient distribution is reconstructed using the Landweber iteration algorithm and substituted into the nonlinear equation set for further simplification. Finally, the velocity distribution is reconstructed by solving the simplified equation group via the interior-point algorithm. The proposed method is validated numerically by reconstructing the velocity distribution of water molecules, as calculated by Computational Fluid Dynamics, over a cross-section of a double-mode scramjet combustor. The method does not require adding extra tracer particles and avoids issues arising from the short lifetime of molecular tags. It is suitable for diagnosis of high-speed flow fields.

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Section: Discussionmentioning

confidence: 99%

“…However, in previous applications, most efforts were devoted to line-of-sight LAS, which could only measure the bulk velocity of the gas flow. Gamba reported the reconstruction of the spatiallyresolved velocity distribution [18]. In his work, the spectral absorbance profile was approximated by the discrete Fourier transform (DFT).…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of two-dimensional velocity distribution in scramjet by laser absorption spectroscopy tomography

Cao

et al. 2018

Appl. Opt.

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In situ measurement on nonuniform velocity distribution in external detonation exhaust flow by analysis of spectrum features using TDLAS

Huang¹,

Li²,

Weng³

et al. 2022

Chinese Phys. B

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Instantaneous and precise velocity sensing is a critical part of research on detonation mechanism and flow evolution. This paper presents a novel multi-projection tunable diode laser absorption spectroscopy solution, to provide a real-time and reliable measurement of velocity distribution in detonation exhaust flow with obvious nonuniformity. Relations are established between overlapped spectrums along probing beams and Gauss velocity distribution phantom according to the frequency shifts and tiny variations in components of light-of-sight absorbance profiles at low frequencies analyzed by the fast Fourier transform. With simulated optical measurement using H2O feature at 7185.6 cm−1 carried out on a phantom generated using a simulation of two-phase detonation by a two-fluid model, this method demonstrates a satisfying performance on recovery of velocity distribution profiles in supersonic flow even with a noise equivalent absorbance up to 2 × 10−3. This method is applied to the analysis of rapidly decreasing velocity during a complete working cycle in the external flow field of an air-gasoline detonation tube operating at 25 Hz, and results show the velocity in the core flow field would be much larger than the arithmetic average from traditional tunable diode laser doppler velocimetry. This proposed velocity distribution sensor would reconstruct nonuniform velocity distribution of high-speed flow in low cost and simple operations, which broadens the possibility for applications in research on the formation and propagation of external flow filed of detonation tube.

show abstract

Multi-parameter estimation for spatially-resolved measurement of two-component velocity using absorption tomography

Cited by 2 publications

References 29 publications

Reconstruction of two-dimensional velocity distribution in scramjet by laser absorption spectroscopy tomography

Reconstruction of two-dimensional velocity distribution in scramjet by laser absorption spectroscopy tomography

In situ measurement on nonuniform velocity distribution in external detonation exhaust flow by analysis of spectrum features using TDLAS

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