Experimental study of fluid flows in general and combustion in particular requires techniques that are non-intrusive: they should not affect the phenomenon under study. Optical diagnostics is undoubtedly the most powerful class of such techniques, and we have a wide range available. Experimental facilities include not only a variety of (often laser-based) diagnostic techniques, but also optically accessible combustion and flow equipment. Much of our work uses spectroscopic techniques to single out individual chemical species.
Available optical techniques:
- Particle Image Velocimetry (PIV)
- Schlieren & Shadowgraphy
- Diffused Back-illumination Imaging (DBI)
- Chemiluminescence imaging
- (Planar) Laser Induced Fluorescence ((P)LIF)
- (Planar) Laser Induced Phosphorescence ((P)LIP)
- Spontaneous Raman & Rayleigh Scattering
- (Hi-speed) laser-Induced Incandescence ((HS)LII)
- Interferometric Particle Imaging (IPI)
Available test rigs:
- Optically accessible heavy-duty CI engine
- Optically accessible light-duty CI engine
- Constant-volume spray vessel
- Various dedicated burner systems
Composite image of the structure of a fuel spray under conditions relevant for heavy-duty Diesel engines (made by Noud Maes). The fuel spray enters at the left, and is recorded 700 µs after start-of-injection (aSOI). White line: vapour boundary of an inert spray (Schlieren); Blue line: liquid boundary (DBI); Green: electronically excited OH radicals (flame front; chemiluminescence); Red: formaldehyde (low-temperature reactions; PLIF).
Raman spectrum of a non-premixed n-heptane doped with a few percent of toluene (made by Robin Doddema). The horizontal axis represents the Raman shift, the vertical axis the height above the burner exit.