Characterization of Temperature Distributions in a Swirled Oxy-fuel Coal Combustor using Tomographic Absorption Spectroscopy with Fluctuation Modelling

Abstract Oxy-fuel combustion promises efficient and inexpensive carbon dioxide sequestration and is therefore subject to active experimental research. However, the transfer of mature, non-intrusive diagnostic methods for temperature measurement like Coherent Anti-Stokes Raman Spectroscopy (CARS) from air-fed to oxy-fuel systems is challenging due to the deficiency in diatomic species suitable for thermometry. Although not limited to oxy-fuel atmospheres, we demonstrate the application of linear hyperspectral absorption tomography on water vapor in a swirled oxy-fuel coal combustor as a complementary diagnostic method, supplementing reference and validation data sets. Due to the burner design an axisymmetric reconstruction of the time-averaged temperature field is conducted. To compensate the temperature bias expected when evaluating time-averaged spectroscopic data we incorporate turbulent temperature fluctuations into our spectroscopic model, providing a fluctuation measure in addition to mean temperatures. The results quantitatively agree with vibrational O 2 -CARS measurements and qualitatively recreate spatial structures known from particle image velocimetry (PIV) flow fields.