Study of the absorption characteristics of molecular oxygen in the Schumann-Runge system at high temperatures: I. Calculations of absorption spectra

Bykova, N. G.; Kuznetsova, L. A.

doi:10.1134/s0030400x08110040

Cited by 25 publications

(8 citation statements)

References 3 publications

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“…At t ≤ t m , the concentration of the oxygen molecules n changes during vibration excitation only slightly and this variation is taken into account in processing the experimental data. The temperature T v increases and can be determined from a single experiment by comparing the cross-section measured σ with the value σ = f (T, T v ) calculated using the ¤Spectrum¥ software [2]. The cross-section measured can be calculated from the relation σ = − ln(I/I 0 )/(nl).…”

Section: Temperature T Fr ≤ 6000 Kmentioning

confidence: 99%

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Experimental study and numerical modeling of vibrational oxygen temperature profiles behind a strong shock wave front

Забелинский

Ibraguimova

Shatalov

et al. 2012

Progress in Flight Physics

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The evolution of oxygen molecule vibrational temperature behind the front of a shock wave was studied at shock wave velocities 3 4.5 km/s and gas pressure ahead of the shock front 1 5 Torr. The results of vibrational temperature measurement con¦rmed the conception of separation of vibrational relaxation and dissociation zones behind the shock wave front at T ≤ 6500 K. It is observed that at T = 6500 10 500 K the vibrational temperature decreased in comparison with its value characterized by the achievement of vibrational translational equilibrium before the dissociation started. It is shown that the model should to be modi¦ed to describe the evolution of the oxygen vibrational temperature under the conditions of vibrational relaxation and dissociation coupling.

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Section: Temperature T Fr ≤ 6000 Kmentioning

confidence: 99%

“…In this connection, the cross sections calculated for thermally equilibrium conditions in a gas using the ¤Spectrum¥ software [2] were ¦rst tested by comparing with the cross sections measured also in equilibrium conditions [3].…”

Section: Introductionmentioning

confidence: 99%

Experimental study and numerical modeling of vibrational oxygen temperature profiles behind a strong shock wave front

Забелинский

Ibraguimova

Shatalov

et al. 2012

Progress in Flight Physics

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“…In these experiments, the absorption of laser radiation at several wavelengths between 230 and 260 nm was interpreted in terms of translational and vibrational temperatures of the nonequilibrium gas. Bound-bound and boundcontinuum transitions from 3 X − g to B 3 Σ − u state were considered for all vibrational states, assuming a Boltzmann population of energy levels [63]. One should note that, due to the multitemperature assumption used in [63] to estimate the absorption coefficient, the comparison of experimental data and the state-to-state (STS) model should be done with caution.…”

Section: Vibrational and Rotational Relaxation Timesmentioning

confidence: 99%

Kinetic Models of Oxygen Thermochemistry Based on Quasi-Classical Trajectory Analysis

Andrienko

Boyd

2018

Journal of Thermophysics and Heat Transfer

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Recent progress in state-resolved kinetic models of thermal relaxation and dissociation of oxygen based on highfidelity transition rate coefficients is presented. Specifically, three types of collisions encountered in high-temperature flows are discussed: O 2-O, O 2-N, and O 2-N 2. For these molecular systems, the thermal relaxation times and dissociation rate coefficients, obtained from extensive trajectory simulations, are compared with existing experimental data. A new set of calculations for O 2-N 2 on an ab-initio potential energy surface is presented. Accuracy of multitemperature models is assessed based on comparison with the solution of master equations. Recommendations for adjustable parameters employed in multitemperature models are provided.

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“…We obtained absorption calculations for our test conditions using the "Spectrum" model developed by Bykova and Kuznetsova [12] through private communication with the authors. The Spectrum model calculates the absorption of oxygen in the UV due to the Schumann-Runge B 3 Σ − u ←X 3 Σ − g system, including contributions from both bound-unbound transitions that make up the SchumannRunge continuum as well as the bound-bound transitions that make up the Schumann-Runge bands.…”

Section: A Absorption Modelmentioning

confidence: 99%

“…Using the Spectrum absorption model [12], the oxygen absorbance was calculated as a function of time during the dissociation behind the reflected shock from the measured pressure and calculated temperature and oxygen mole fraction. This modeled absorbance was then compared to the measured absorbance, and the preexponential factor A, of reaction 1, the dissociation due to argon, was adjusted until the model matched the measurement.…”

Section: Dissociation Modelmentioning

confidence: 99%

Measurements of Oxygen Dissociation Using Laser Absorption

Owen

Davidson

Hanson

2016

Journal of Thermophysics and Heat Transfer

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The dissociation rate coefficient for oxygen in argon, O 2 Ar ⇌ O O Ar, was measured using laser absorption near 216 nm in the Schumann-Runge system in a shock tube. A mixture of 2% oxygen in argon was studied behind reflected shocks at initial equilibrium temperatures from 4400 to 7900 K and pressures from 0.2 to 1 atm. The dissociation was modeled decoupled from vibrational relaxation because dissociation was evident only after the test gas mixture was near vibrational equilibrium. The dissociation rate coefficient was determined by fitting the measured oxygen absorbance time history for each experiment using temperatures based on the incident shock speed and the shock relations and adjusting the A-factor of the dissociation rate coefficient. Good agreement was found with the prior experimental work and model of Camac and Vaughan. Consistent results were also obtained for measurements with constant pressure as well as increasing pressure, validating our method to account for pressure changes by including the pressure profile in the dissociation model. Nomenclature Abs = absorbance A= preexponential factor in modified Arrhenius equation b = preexponential factor in modified Arrhenius equation E a = activation energy, kcal∕mol I = laser beam intensity exiting shock tube, W I 0 = laser beam intensity entering shock tube, W I o = incident intensity ratio I t = transmitted intensity ratio k d = dissociation rate coefficient (for second order), cm 3 ∕mol · s P = pressure, atm P i = initial postshock pressure, atm R = 1.9858775, universal gas constant, cal∕mol · K T eq = equilibrium temperature, K t = time, s v 0 0 = vibrational level

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Study of the absorption characteristics of molecular oxygen in the Schumann-Runge system at high temperatures: I. Calculations of absorption spectra

Cited by 25 publications

References 3 publications

Experimental study and numerical modeling of vibrational oxygen temperature profiles behind a strong shock wave front

Experimental study and numerical modeling of vibrational oxygen temperature profiles behind a strong shock wave front

Kinetic Models of Oxygen Thermochemistry Based on Quasi-Classical Trajectory Analysis

Measurements of Oxygen Dissociation Using Laser Absorption

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