K.P. Geigle, J. Zerbs, C. Guin

Soot is one of the most discussed pollutants in ground and air traffic. Moreover, ist effect as source of intense radiation is significant as soon as local rich mixtures occur, especially at increased pressure. Motivation for soot research is the need to understand soot chemistry for soot formation and oxidation in turbulent, pressurised environment in order to prevent ist emission as much as possible. A detailed understanding of the underlying processes can be gained when correlating sophisticated CFD modelling with well defined but yet realistic validation experiments. Within the EU project TLC (Towards Lean Combustion) several experimental tasks are devoted to optimising laser-based diagnostics with ONERA and DLR contributing. One of the contained tasks is dealing with application of laser-induced incandescence (LII) as a tool to determine soot distributions inside the combustor quantitatively. Trends are presented showing soot distributions upon changes of the combustor operating conditions between 4 and 23 bars at realistic geometries and flow rates. In general, the soot concentrations were found to be relatively low. But prior to the final steps of data reduction, interferences from unexpected effects had to be reduced: during the experiments plasma formation at the combustors base plate, preventing the high power laser beam from exiting the combustor, turned out to be a critical issue. In contrast to the defined LII excitation wavelength at 1064 nm, which can be removed by suitable filtering, the strong resulting broadband plasma radiation was present in the images illuminating combustor walls and flanges. Due to their different dynamics and different statistical behaviour, LII events can be distinguished from plasma radiation; suitable data analysis routines are presented leading to relatively undisturbed soot distributions. The resulting soot average distributions are well suited to determine the positions of soot formation and oxidation as well as quantification of soot concentrations under the highly challenging technical conditions given. Together with data from other tasks (OH and kerosene distributions), studied by ONERA, an excellent validation data set will be available for soot modellers, while the respective industry partners receive a good impression of the low emission capability of their combustor.

Deutscher Luft- und Raumfahrtkongress 2010

Conference Paper

englisch

21,0 x 29,7 cm, 7 Seiten

Deutscher Luft- und Raumfahrtkongress Tagungsband - Manuskripte, 2010, 2010, ; S.571-577; 2010; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

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Bestellbar

2010