In the present study laminar and turbulent oxy-fuel jet flames are investigated
both experimentally and numerically with emphasis on the direct comparison of the
Rayleigh signal. The Rayleigh signal was measured for both flame setups, correcting for
background light appropriately. Two downstream regions were recorded for the laminar
flame and three for the turbulent flame. Equivalently, the signal was processed numerically
based on the numerical species data and temperature. The laminar flame was used
for validating the procedure of processing the Rayleigh signal. Both the numerical species
data and the temperature are known from detailed simulations, so a predicted Rayleigh
signal can easily be obtained. Further, the influence of the choice of the kinetic mechanism,
radiation and diffusion model was investigated. In contrast, in the turbulent Large
Eddy Simulation, the Rayleigh signal has to be computed using an appropriate turbulencechemistry interaction model in order to obtain the Reynolds-filtered Rayleigh signal which is of non-linear nature. In the present investigation, the Rayleigh signal was incorporated in the flamelet/progress variable approach. The statistics of the experimental and numerical Rayleigh signal were then compared. The proposed procedure of directly comparing the
experimental and predicted Rayleigh signal was shown to be advantageous in model validation especially in turbulent flame configurations. The procedure enables accurate model validation across an entire 2D field of view whilst using a realistic fuel-oxidizer combination and reducing experimental complexity.