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2026 Vol.31, Issue 3 Preview Page

Research Article

Estimation of Flame Temperature Using the Background-Oriented Schlieren Technique (BOS)

배경 지향형 슐리렌 기법(BOS)을 이용한 화염 온도 추정

Muhammad Nouman Rafiq1
,
Seojeong Park1
,
Hyemin Kim1†
무하마드 노우만 라피크1
,
박 서정1
,
김 혜민1†
1Department of Aeronautical and Mechanical Design Engineering, Korea National University of Transportation
1국립한국교통대학교 항공·기계설계학과
*Corresponding Author
30 September 2026. pp. 47-54
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Abstract

This study applied background-oriented schlieren (BOS) to reconstruct radial temperature distributions of a premixed propane-air flame at equivalence ratios of 0.9, 1.0, and 1.1. Background-image displacements were obtained using PIVlab and converted into temperature through deflection-angle calculations, Abel inversion, the Gladstone-Dale relation, and the ideal gas law. The reconstructed fields revealed a clear dependence on flame condition: the stoichiometric flame exhibited the strongest and widest high- temperature region, the lean flame showed a reduced thermal intensity, and the rich flame displayed a more localized hot core near the centerline. Radial temperature profiles at y = 30 mm were validated against corrected thermocouple measurements. BOS captured the overall radial decay from the flame core to ambient conditions. Quantitatively, the stoichiometric and rich flames showed better agreement, with mean absolute error (MAE) and root mean square error (RMSE) values of 33.19 and 44.28 K and 35.86 and 38.75 K, respectively, while the lean flame exhibited larger errors of 70.08 and 91.67 K. These deviations occurred mainly near the central axis and may be linked to weaker refractive-index gradients and inversion sensitivity. Sequential reconstruction over 0.5 s indicated that the temperature-field structures were generally maintained, thereby demonstrating the potential of BOS for non-intrusive flame-temperature estimation. However, improved centerline validation and further uncertainty quantification are still required.

Keywords
Background-oriented schlieren (BOS) technique
Flame temperature
Abel inversion
Thermocouple validation
Refractive-index reconstruction
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Information
  • Publisher :The Korean Society of Combustion
  • Publisher(Ko) :한국연소학회
  • Journal Title :Journal of the Korean Society of Combustion
  • Journal Title(Ko) :한국연소학회지
  • Volume : 31
  • No :3
  • Pages :47-54
  • Received Date : 2026-07-06
  • Revised Date : 2026-08-10
  • Accepted Date : 2026-08-10
  • DOI :https://doi.org/10.15231/jksc.2026.31.3.047
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