Temperature measurements are ubiquitous in combustion systems. However, the accuracy of surface temperature measurements of critical components operating in a harsh combustion gases environment is greatly affected by reflection and combustion gas radiation. In this paper, an analytical two-color pyrometry model was used to quantitatively analyze the temperature errors caused by the combination of reflection and HO-CO-CO-N mixture radiation. As the results indicate, the most significant contributors to the measurement errors are found to be the error arising from HO-CO-CO-N mixture absorption and emission for two-color pyrometer operating at long wavebands. The errors due to reflection predominate over the measurement errors measured at short wavebands. In a combustor where reflected radiation from high-temperature surrounding and hot/cool combustion gas is present, two-color pyrometry is practically inoperative as a consequence of its unacceptably large measurement error and high measurement sensitivity. When the intervening gas is isothermal and the optical distance from surface to detector is considered optically thin, the temperature error has linear growth with both the HO-CO-CO-N mixture concentration and viewing path length increasing. This linear change provides us a method of linear extrapolation to eliminate the effect of uncertain gaseous absorption and emission. The results of this work can be used as a theoretical support for the design and application of a two-color pyrometer in a gas-fired furnace.
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http://dx.doi.org/10.1364/OE.433942 | DOI Listing |
For reliable tomographic measurements the underlying 2D images from different viewing angles must be matched in terms of signal detection characteristics. Non-linearity effects introduced by intensified cameras and spatial intensity variations induced from inhomogeneous transmission of the optical setup can lead, if not corrected, to a biased tomographic reconstruction result. This paper presents a complete correction procedure consisting of a combination of a non-linearity and flatfield correction for a tomographic optical setup employing imaging fiber bundles and four intensified cameras.
View Article and Find Full Text PDFMeasurement of chemical species and temperature mapping in flames is essential to understanding the combustion process. Multiple cameras are conventionally employed for measurement in such scenarios making the experimental setup not only cost-intensive but also challenging. To circumvent this, structured illumination (SI)-based methods are reported for multispecies chemiluminescence (CL) imaging using a single camera.
View Article and Find Full Text PDFMaterials (Basel)
May 2023
Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, Ernst-Zermelo-Str. 4, 79104 Freiburg, Germany.
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View Article and Find Full Text PDFACS Omega
April 2023
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
The burning and soot characteristics of RP-3 kerosene droplets under sub-atmospheric pressure were experimentally investigated in a pressure chamber. The droplet size during combustion was continuously recorded using a high-speed camera, and the burning rate based on the -law was determined. The flame temperature was calculated from ICCD camera spectral data using two-color pyrometry, and the carbon soot volume fraction was measured by the calibrated laser-induced incandescence (LII) technique.
View Article and Find Full Text PDFA compact and low-cost two-dimensional (2D) thermal imager was developed for real-time temperature mapping of a melt pool during coaxial laser cladding (the additive manufacturing technique). The device combines a color CMOS camera and a compact spectrometer. The spectrometer was utilized for internal calibration and validation of a 2D temperature map that was acquired by the CMOS camera.
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