One of the activities within the LLC is the study of combustion processes using optical diagnostic techniques, the majority of which are based on lasers. Combustion is of central importance in today’s society, mainly for heat and power production, industrial processing, and transportation. Since fossil fuels are not renewable, and pollutants from their combustion contribute to environmental problems such as acid rain, smog and the greenhouse effect, there are clear reasons to decrease their use. Additionally, the increasing use of renewable fuels has introduced new challenges for emission reduction. Research and development in combustion are very important to obtain a fundamental understanding of the underlying processes. With this knowledge higher efficiency, lower fuel consumption, and reduced emissions of pollutants can be achieved.
As a laser beam is transmitted through a combustion environment the interaction between laser photons and atoms/molecules or particles results in scattering or fluorescence, which upon detection can provide information on quantities such as flame temperature and species concentration. Since laser-based techniques rely on the small-scale interaction between light and matter, larger-scale phenomena such as flow field and combustion chemistry are unaffected, making the methods nonintrusive. A large variety of techniques are being developed and applied, for example laser-induced fluorescence (LIF) for imaging of species concentrations, coherent anti-Stokes Raman spectroscopy (CARS) for temperature measurements, structured laser illumination for spray characterization, laser-induced incandescence (LII) for characterization of soot particles, and laser radar (LIDAR) concepts for single-ended diagnostics over large distances.
Fundamental and applied research
The research being carried out covers both technique development and applications for combustion research. Some studies are oriented towards phenomenological investigations of combustion processes and cold flows, while others are of a more applied nature, where the same processes are investigated in practical combustion devices, such as internal combustion engines and gas turbines.