Raman Line Imaging for the Quantification of the Fuel/Air-Ratio during Jet-Mixing at Diesel Relevant Conditions
13:30 - 14:00
Level 0 lecture hall between Al-Jazri and Al-Kindi (buildings 4 and 5)
Quantitative fuel/air-ratio measurements were made during jet-mixing when a fuel jet was injected with a diesel injector into a high-pressure & high temperature nitrogen atmosphere. The high-temperature & high-pressure chamber was continuously flushed with nitrogen (less than 2% oxygen still contained) at stationary diesel relevant conditions (up to 60 bar & 923 K). Fuel-jets were injected with a repetition rate of 1 Hz. Ethanol and decane as well as blends of ethanol and decane were used as fuel.
The fuel/air-ratio was quantified spatially resolved along a one-dimensional probe volume (line) using a Raman setup that imaged the excitation laser beam waist under 90°. The probe volume featured a length of 6.4 mm and could be resolved in increments of 128 µm. Due to the availability of a long-pulse laser, single-shot measurements were possible within one excitation pulse of 1 µs pulse duration. Raman measurements were made with a repetition rate of 1 Hz and were synchronized to the fuel injection events.
During the presentation special attention will be laid on the realization of the Raman setup, the strategy of calibrating the Raman setup at diesel relevant conditions and the evaluation of the Raman spectra. Next to quantitative fuel/air-ratios also some information about the state-of-phase of the mixture can be extracted from the Raman spectra, if pure ethanol is taken as the fuel.
The project leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under ERC starting grant agreement No. 637654 (Inhomogeneities) as well as from the FNR (Fachagentur für Nachwachsende Rohstoffe, engl: Agency for renewable resources) and the Federal Ministry of Food and Agriculture (BMEL).