Development of methods

Laser-induced incandescence (LII)
(measurement of soot volume fraction and soot particle size)



The figures show an instantaneous soot distribution (upper frame) and the average soot distribution (middle) in comparison to the visual impression (photo in lower frame) in a turbulent jet flame (ONERA/DLR). The soot distributions were measured by LII.

Laser-induced incandescence permits quantitative determination of soot volume fractions when the method is calibrated using extinction measurements. Our work is aimed at establishing laser-induced incandescence as a reliable measurement technique for application in turbulent high-pressure combustion like gas turbine combustion chambers. Systematic tests are carried out on high-pressure burners using various fuels, including liquid fuels, in a wide range of stoichiometry and pressures. Evaluating the decay of the LII signal over time permits determination of the primary particle size of the soot produced during combustion.


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