High-temperature laser absorption diagnostics for CH2O and CH3CHO and their application to shock tube kinetic studies

摘要: Abstract Laser absorption diagnostic methods were developed for the quantitative measurement of formaldehyde (CH2O) and acetaldehyde (CH3CHO) at high temperatures in shock tube kinetic studies. Investigation high-temperature CH2O spectrum has shown that optimal wavelength detection using commercially available lasers is near 2896 cm−1. By exploiting structural difference between spectra broadband interfering species, a two-color (2895.92 cm−1 2895.60 cm−1) interference-free scheme sensing combustion environment was developed. A third color (32601.10 cm−1) also been added to develop UV/IR combined CH3CHO/CH2O measurements. To implement these schemes, aldehyde cross-sections all three colors measured behind reflected waves over wide span (600–1800 K) pressures (0.8–3.6 atm), with an uncertainty ±5%, schemes validated two controlled experiments well-established chemistry. Applications diagnostics demonstrated pyrolysis 1,3,5-trioxane, CH3CHO. The unimolecular decomposition rate 1,3,5-trioxane determined 869–1037 K average pressure 2.1 atm: kI = 3.58 × 1012 exp (−18,590 K/T) s−1, overall less than 20%.