ONERA, 91120 Palaiseau
Développement des techniques optiques pour la caractérisation in-situ de la suie dans des foyers de combustion à haute pression
The predicted significant growth in air traffic urges for new research in combustion particularly in two directions: 1) to improve fuel efficiency to cope with diminishing fossile ressources and 2) to curb down combustion emissions with respect to environmental and climate issues. The solution to the first issue seems to lie in combustion at higher temperatures and pressures but this can have a negative impact on the second issue particularly concerning soot emissions. ONERA can play a key role in this research as it has a long experience in combustion studies carried in its large panel of facilities and with the help of non intrusive optical diagnostics tools.
The objective of the thesis work is to extend and/or develop the techniques which can characterize soot formation and emissions at high temperature and pressure conditions. Laser induced incandescence (LII), sensitive to mature and carbonized soot particles, is the key technique on which efforts will be concentrated. But it’s coupling to other techniques can be quite helpful to complete our understanding of soot kinetics. These complementary tools are LIF (Laser induced Fluorescence observing soot precursors PAH and other combustion parameters like OH), LE (laser extinction which can help distinguish different soot types using different wavelengths and useful also to calibrate LII for quantitative measurements) and SSE (Soot Spectral Emissions for soot temperature estimations).
The experimental work will start by studying the coupling of these techniques in well known low pressure (atmospheric) conditions (McKenna and/or classical burners). Then, gradually, their response will be studied at higher pressures in a monodisperse burner implemented on a high-pressure chamber up to 20 bars before applications in research test rigs like the newly developed MICADO facility. Another important facility long waiting such measurements is the Mascotte cryogenic combustion test rig with pressures up to 60 bars.
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