Application: Combustion diagnostics, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Pinkowski, Nicolas Hunter; Ding, Yiming; Strand, Christopher L.; Hanson, Ronald K.; Horvarth, Raphael; Geiser, Markus
Measurement Science and Technology; 2020
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In the current study, a quantum-cascade-laser-based dual-comb spectrometer (DCS) was used to paint a detailed picture of a 1.0 ms high-temperature reaction between propyne and oxygen. The DCS interfaced with a shock tube to provide pre-ignition conditions of 1225 K, 2.8 atm, and 2% p-C3H4/18% O2/Ar. The spectrometer consisted of two free-running, non-stabilized frequency combs each emitting at 179 wavelengths between 1174 and 1233 cm−1. A free spectral range, {f_r}, of 9.86 GHz and a difference in comb spacing, {Delta }{f_r}, of 5 MHz, enabled a theoretical time resolution of 0.2 µs but the data was time-integrated to 4 µs to improve SNR. The accuracy of the spectrometer was monitored using a suite of independent laser diagnostics and good agreement observed. Key challenges remain in the fitting of available high-temperature spectroscopic models to the observed spectra of a post-ignition environment.
Application: Combustion diagnostics, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Guangle Zhang, Raphael Horvath, Dapeng Liu, Markus Geiser, Aamir Farooq
Sensors, MDPI; 2020
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Rapid multi-species sensing is an overarching goal in time-resolved studies of chemical kinetics. Most current laser sources cannot achieve this goal due to their narrow spectral coverage and/or slow wavelength scanning. In this work, a novel mid-IR dual-comb spectrometer is utilized for chemical kinetic investigations. The spectrometer is based on two quantum cascade laser frequency combs and provides rapid (4 µs) measurements over a wide spectral range (~1175–1235 cm−1). Here, the spectrometer was applied to make time-resolved absorption measurements of methane, acetone, propene, and propyne at high temperatures (>1000 K) and high pressures (>5 bar) in a shock tube. Such a spectrometer will be of high value in chemical kinetic studies of future fuels.
Application: Combustion diagnostics, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Pinkowski, N.; Strand, C. L.; Ding, Y.; Hanson, R. K.; Geiser, M.; Horvath, R.
Presentation at ISSW32; 2019
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Application: Combustion diagnostics, Gas analysis, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Peter Fjodorow, Pitt Allmendinger, Raphael Horvath, Jürgen Herzler, Florian Eigenmann, Markus Geiser, Mustapha Fikri and Christof Schulz
Applied Physics B volume 126, Article number: 193; 2020
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A dual-frequency-comb spectrometer based on two quantum-cascade lasers is applied to kinetics studies of formaldehyde (HCHO) in a shock tube. Multispectral absorption measurements are carried out in a broad spectral range of 1740–1790 cm–1 at temperatures of 800–1500 K and pressures of 2–3 bar. The formation of HCHO from thermal decomposition of 1,3,5-trioxane (C3H6O3, 0.9% diluted in argon) and the subsequent oxidation of formaldehyde is monitored with a time resolution of 4 µs. The rate coefficient of the decomposition of C3H6O3 (i.e., HCHO formation) is found to be k1 = 6.0 × 1015 exp(− 205.58 kJ mol−1/RT) s–1. For the oxidation studies, mixtures of 0.36% C3H6O3 and 1% O2 in argon are used. The information of all laser lines, along with the consideration of individual signal variance of each line, is utilized for kinetic and spectral analysis. The experimental kinetic profiles of HCHO are compared with simulations based on the mechanisms of Zhou et al. (Combust Flame, 197:423–438, 2018) and Cai and Pitsch (Combust Flame, 162:1623–1637, 2015).