SPATIALLY-RESOLVED RAMAN-SCATTERING FOR MULTISPECIES AND TEMPERATURE ANALYSIS IN TECHNICALLY APPLIED COMBUSTION SYSTEMS - SPRAY FLAME AND 4-CYLINDER IN-LINE ENGINE

Spatially resolved Raman scattering is used to measure the single shot stoichiometry before ignition inside a realistic internal combustion engine with high single shot precision of 1%-4% (depending on the exte nt of spatial averaging). The high precision results from the simultan eous detection of fuel and N2 (O2), which yields stoichiometry via a r elative measurement. The cycle-to-cycle fluctuations of stoichiometry are clearly resolved. The feasibility of averaged spatially resolved s imultaneous multi-species detection is demonstrated in a commercial oi l-burning furnace as well. The limited precision that is usually obtai ned in Raman scattering by interfering emissions is highly improved us ing the fact that the interfering emission is unpolarized whereas Rama n scattering is highly polarized. Therefore, Raman measurements provid ed good signal-to-noise ratios in the spray flame even in the area whe re fuel droplets occur and during combustion in the engine. The optica l multichannel analyzer yields one-dimensional spatial resolution, and offers the capability to easily combine Raman scattering with Rayleig h scattering and laser-induced fluorescence detection of minority spec ies.