Acetylene (C 2 H 2 ), as an important precursor for chemiluminescence species, is a key to understand, simulate and model the chemiluminescence and the related reaction paths. Hence we developed a high resolution spectrometer based on direct Tunable Diode Laser Absorption Spectroscopy (TDLAS) allowing the first quantitative, calibration-free and spatially resolved in situ C 2 H 2 measurement in an atmospheric non-premixed counter-flow flame supported on a Tsuji burner. A fiber-coupled distributed feedback diode laser near 1535 nm was used to measure several absolute C 2 H 2 concentration profiles (peak concentrations up to 9700 ppm) in a laminar non-premixed CH 4 /air flame (T up to 1950 K) supported on a modified Tsuji counter-flow burner with N 2 purge slots to minimize end flames. We achieve a fractional optical resolution of up to 5 × 10 −5 OD (1σ ) in the flame, resulting in temperaturedependent acetylene detection limits for the P17e line at 6513 cm −1 of up to 2.1 ppm·m. Absolute C 2 H 2 concentration profiles were obtained by translating the burner through the laser beam using a DC motor with 100 µm step widths. simulations using our new hydrocarbon oxidation mechanisms show excellent agreement in position, shape and in the absolute C 2 H 2 values.
The lifetime of thermographic phosphors needs to be short enough to resolve the temperature time scales and long enough to be properly resolved by the respective detector. Up until now, there has not been a thermographic phosphor that exhibits an adequate temperature lifetime characteristic for two-dimensional thermometry inside internal combustion engines using high speed cameras. Hence, this study suggests the material Gd 3 Ga 5 O 12 :Cr for this purpose. The emission spectra and the temperature lifetime characteristics were determined and the lifetime is shown to be independent of the composition and the absolute pressure of the surrounding gas phase.
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