LASER MEASUREMENTS OF SCALARS IN TURBULENT-DIFFUSION FLAMES

Laser diagnostics based on incoherent interaction between light and matter can provide quantitative scalar data in reacting flows as linear calibration procedures are achievable. However, in turbulent diffusion flames, where mixing and chemistry interact, a closure relation is still required as the signal intensity depends on both the instantaneous composition and the reaction progress in the probed volume. The properties of the main scalars in tubulent non-premixed flames are examined in order to provide coupling functions that can be used to complete the laser diagnostics, and also to underline the quantities and assumptions that are worth experimental investigation. Laser measurements by Mie, Rayleigh, Raman and induced fluorescence techniques are successively reviewed as well as recent combined measurements where two diagnostics are simultaneously performed to provide correlated data which are essential for interpretation.