Flame Temperature Measurement Techniques

Accurate determination of flame temperature underpins advances in combustion science, energy conversion and emission control. Traditional contact probes such as thermocouples offer simplicity but suffer perturbation and limited bandwidth. Non-intrusive optical approaches have therefore become predominant, exploiting emission, absorption or scattering of light by flame species. Two-colour pyrometry and laser absorption spectroscopy extract temperature from wavelength-dependent emission or attenuated beam intensities, whereas hyperspectral and infrared imaging provide spatially resolved fields. Tomographic reconstruction and light field imaging extend these methods into three dimensions by inverting radiative transfer models. Recent progress has focused on enhancing temporal resolution to capture transient events, reducing computational load through novel sampling strategies, and refining emissivity calibration via spectral or dopant markers. Together, these innovations support real-time diagnostics in engines, industrial burners and research facilities, while minimising uncertainty in reactive flows and pollutant formation studies.

Research from Nature Portfolio

Recent theoretical work has refined the fundamental basis of optical pyrometry by revisiting the shape of blackbody emission curves. Two new parameters, relative width and symmetric factor, have been defined to characterise spectral profiles more rigorously than peak-wavelength approaches. By establishing analytic relationships between these metrics and absolute temperature, the method promises improved calibration of optical thermometers and enhanced accuracy in high-temperature environments. This advance may inform future standards for non-contact temperature sensing and guide development of compact radiometric instruments.

Flame Temperature Measurement Techniques publication trend

The graph below shows the total number of articles in flame temperature measurement techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Blackbody radiation: Idealised emission from an object that absorbs all incident radiation, with spectral profile solely determined by temperature.

Emissivity: Ratio of an object’s radiation intensity to that of a perfect blackbody at the same temperature and wavelength.

Radiative transfer: Modelling of energy transport by emission, absorption and scattering of photons through a medium.

Light field imaging: Capture of angular and spatial information of light rays in a single exposure, enabling three-dimensional reconstructions.

Laser-induced breakdown spectroscopy (LIBS): Analytical technique in which a focused laser pulse creates a micro-plasma, and emitted light is analysed to identify elemental composition.

References

1. Exact research on the theory of the blackbody thermal radiation. Scientific Reports (2016).
2. Approach to reduce light field sampling redundancy for flame temperature reconstruction.. Optics Express (2021).
3. Edge Effects on Simultaneous Reconstructions of Flame Temperature and Soot Volume Fraction Profiles by a CCD Camera. Sensors (2022).
4. Two-Dimensional Flame Temperature and Emissivity Distribution Measurement Based on Element Doping and Energy Spectrum Analysis. IEEE Access (2020).