[en] In this work, the fluorescence properties of the fuel tracer 1-methylnaphthalene (1-MN) are investigated in a calibration flow cell at elevated temperatures and pressures. This fuel tracer is well suited to investigate mixture formation in diesel engine applications, as 1-MN is a natural diesel fuel component. A tracer-LIF (laser-induced fluorescence) concept is developed that enables temperature measurements using a two-color approach in oxygen-containing gas mixtures. Furthermore, the potential for simultaneous measurement of equivalence ratio (fuel–air ratio, FAR) is evaluated. First, a picosecond Nd:YLF-laser at 263 nm in combination with a spectrograph and a streak unit was used to investigate the spectral fluorescence emission and fluorescence lifetimes. In addition, a nanosecond Nd:YAG-laser at 266 nm was used for fluorescence calibration with regard to equivalence ratio and temperature. All measurements were performed in an oxygen-containing environment at different equivalence ratios, temperatures up to 800 K and pressures up to 2.5 MPa. The dependency of the fluorescence emission on equivalence ratio was studied for varied fuel amount and air concentrations. The calibration data form the basis for investigations of fuel distribution and temperature under realistic engine conditions in an oxygen-containing environment.

[en] In this work, the UV absorption cross sections of the fluorescence tracer 1-methylnaphthalene are determined in the range of 230–330 nm. The experiments are performed in a continuously scavenged gas flow cell, which allows for defined homogeneous conditions regarding temperature, pressure, and tracer/fuel composition. A LSDS (laser driven light source) is used for irradiation, which enables high spectral emission intensities in the UV range studied. For detection, a spectrograph in combination with an intensified camera is applied. Absorption cross sections at temperatures up to 850 K are determined and compared to sparsely available published data. Possible uncertainties caused by the optical setup and the flow cell, respectively, are considered.