Line-of-sight gas radiation effects on near-infrared two-color ratio pyrometry measurements during plasma wind tunnel experiments

Andrea Fagnani, Bernd Helber, Annick Hubin, Olivier Chazot

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Two-color ratio pyrometry is commonly used to measure the surface temperature of aerospace materials during plasma wind tunnel experiments. However, the effect of the plasma radiation on the measurement accuracy is often neglected. In this paper, we formulate a model of the instrument response to analyze the systematic error induced by the gas radiation along the optical path. CFD simulations of the plasma flow field, together with a radiation code, allow to compute the gas spectral radiance within the instrument wavelength range. The measurement error is numerically assessed as a function of the true object temperature and emissivity value. Our simulations explain the typical behavior observed in experiments, showing that a significant bias can affect the measured temperature during the material heating phase. For an actual experiment on a ceramic-matrix composite, a correction to the measured data is proposed, while comparative measurements with a spectrometer corroborate the results.

Original languageEnglish
Article number114175
JournalMeasurement: Journal of the International Measurement Confederation
Volume227
DOIs
Publication statusPublished - 15 Mar 2024

Bibliographical note

Funding Information:
The research of A. Fagnani was funded by the Research Foundation - Flanders, Belgium (dossier n. 1SB3221N). The experimental activities of this work were supported by the Air Force Office of Scientific Research, United States (Grant N. FA9550-18-1-0209). V. Romano is acknowledged for the mesh convergence study on the CF-ICP code simulations. The authors would like to thank J. Freitas Monteiro for the precious help as Plasmatron test engineer and P. Collin as Plasmatron technical operator. S. Szmolka, B. Bras and G. van Papendrecht are acknowledged for the support with the reflectometry measurements at the ESA ESTEC laboratories.

Funding Information:
The research of A. Fagnani was funded by the Research Foundation - Flanders, Belgium (dossier n. 1SB3221N ). The experimental activities of this work were supported by the Air Force Office of Scientific Research, United States (Grant N. FA9550-18-1-0209 ). V. Romano is acknowledged for the mesh convergence study on the CF-ICP code simulations. The authors would like to thank J. Freitas Monteiro for the precious help as Plasmatron test engineer and P. Collin as Plasmatron technical operator. S. Szmolka, B. Bras and G. van Papendrecht are acknowledged for the support with the reflectometry measurements at the ESA ESTEC laboratories.

Publisher Copyright:
© 2024 Elsevier Ltd

Keywords

  • Error analysis
  • Gas emission
  • Plasma wind tunnels
  • Thermal protection materials
  • Two-color pyrometry

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