Retrieval of temperature and extinction coefficient from modulated absorption emission technique: Effects of practical light collection, self-absorption, in-scattering, and finite spatial resolution

Light extinction and emission measurements in soot-laden flames have extensive application for axisymmetric fields where Abel inversion can de-convolve the radial field. The simplified treatment of the radiative transfer equation typically ignores the contributions from signal trapping, in-scattering, physical light collection systems, and finite spatial resolution. A backward Monte Carlo ray tracing methodology is implemented to gauge the validity of these assumptions for high pressure counterflow diffusion flames (CDFs) modelled as an axisymmetric, non-homogeneous, anisotropic, attenuating, and emitting media. Results show that the practical light collection angle is an important parameter with cot θ = α 5%) in absorption and emission signals. • In-scattering contributions in high pressure CDFs result in κ e ≈ κ a . • Signal trapping in OD > 3 flame causes error of ∼ 50% in radiance and 150 K in temperature. • Proposed correction scheme recovers unattenuated signal with slight over-prediction. • Finite and disparate spatial resolution causes ∼ 50 K temperature error for OD > 3 flame.