Shock tube

About: Shock tube is a research topic. Over the lifetime, 6963 publications have been published within this topic receiving 99372 citations.

Emission and absorption measurements on a strongly self-absorbed argon atom line

Abstract: Spectroscopic measurements of the 7635·10 ArI line were made on an argon plasma generated in a free burning arc. The emission profile, corrected for self-absorption, was measured over a temperature range of 10 000°K to 22 000°K at 1 atm pressure. Self-absorption had a strong effect on the measured transition probability but little effect on the temperature profile that was obtained using the Fowler-Milne technique. Kirchhoff's law was used to demonstrate local thermodynamic equilibrium. An iterative technique that corrected line profiles using Kirchhoff's law yielded results that agreed with the measured line profiles. The transition probability measured in this study is 2 1 2 times greater than that reported in a shock tube experiment. Using the measured absorption coefficients, corrections were applied to the shock tube measurement giving a transtition probability that agrees with the one reported in this study.

A shock tube, laser-schlieren study of the pyrolysis of isobutene: Relaxation, incubation, and dissociation rates

Abstract: Dissociation, vibrational relaxation, and unimolecular incubation have all been observed in shock waves in isobutene with the laser-schlieren technique. Experiments covered a wide range of high-temperature conditions: 900–2300 K, and post-incident shock pressures from 7 to 400 torr in 2, 5, and 10% mixtures with krypton. The surprising observation is that of vibrational relaxation, well resolved over the full temperature range. The resolved process is completely exponential, with relaxation times in the range 20–120 ns atm. Relaxation and dissociation are clearly separated for T > 1850 K, with estimated incubation times near 200 ns atm. Incubation is essential for modeling of the very low-pressure decomposition. Modeling of gradients with a chain mechanism initiated by CH fission produces an excellent fit and accurate dissociation rates that show severe falloff. A restricted-rotor, Gorin-model RRKM analysis fits these rates quite well with the known bond-energy as barrier and 〈ΔE〉down = 680 cm−1. The extrapolated k∞ is log k∞(s−1) = 19.187–0.865 log T −87.337 (kcal/mol)/RT, in good agreement with previous work. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 381–390, 2003

Shock-Tube Determination of CN Formation Rate in a CO-N2 Mixture

Abstract: The chemical process of CN formation in a CO-N 2 mixture is studied through temporally resolved intensity measurement of CN violet radiation occurring in the reflected-shock region of a shock tube. A 78% CO-22% N 2 mixture is driven by cold hydrogen to a shock speed of up to 3.45 km/s, to produce a reflected-shock temperature corresponding to Martian entry flight of up to 6.4 km/s. Absolute calibration of spectrometer is performed using a standard lamp of radiance. A reaction model is constructed by combining four existing models and multiplying the C 2 dissociation rate by a factor of five.