Technical Paper
In-Cylinder Measurements of NO Formation in a Diesel Engine
1999-05-03
1999-01-1487
The formation of Nitric oxide (NO) in a Diesel engine has been studied as a function of crank angle through-out the whole combustion cycle, using the Laser Induced Fluorescence (LIF) technique. Measurements were performed in an optically accessible one-cylinder, two-stroke, direct injection Diesel engine. The engine was operated in steady state at different loads and compression ratios. A tunable ArF excimer laser beam was used to excite the NO molecules in the D2∑+(v′=0) ← X2Π(v″=1) band at 193 nm. Dispersed fluorescence spectra allowed to discriminate between NO and interfering oxygen fluorescence. From the spectra, a relative measure for the NO density present in the probed volume of the cylinder was obtained. This density was transformed into an in-cylinder NO content, taking into account the changes in laser intensity, pressure, temperature and volume during the stroke.
