IMAGING AND POST-PROCESSING OF LASER-INDUCED FLUORESCENCE FROM NO IN A DIESEL-ENGINE

The imaging of in-cylinder NO distributions in a steadily running opti cally accessible diesel engine operated on standard diesel fuel is per formed by means of the 2D-LIF technique and a tunable ArF excimer lase r at 193 nm. Simultaneous excitation at 226 nm showed that no sizable photo-chemical effects are induced by the excimer laser. In order to a ccount for the gradually decreasing transparency of the windows due to soot deposits and for the in-cylinder attenuation of the laser intens ity, signal processing procedures for the imaged distributions are pre sented. In addition to the more realistic depictions of NO distributio ns at selected crank angles and loads resulting from these procedures, the latter are an essential step towards a quantitative interpretatio n of the corresponding in-cylinder NO concentrations.