Air Collisional-Radiative Modeling with Heavy-Particle Impact Excitation Processes

Lemal, Adrien; Jacobs, Carolyn; Perrin, Marie‐Yvonne; Laux, Christophe O.; Tran, P.; Raynaud, E.

doi:10.2514/1.t4549

Cited by 15 publications

(9 citation statements)

References 65 publications

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“…Figure shows the results of heavy-particle impact excitation rate measurements as well as theoretical predictions on an Arrhenius plot. Although a few estimates exist for electronic excitation rates due to N–N, N–O, and O–O collisions (relevant to high-temperature air CR models , ), to the authors’ knowledge, these are the first direct shock tube measurements of O* formation rates by O–Ar collisions. Best fits of the current experiments were obtained using the format k M (1, i ) = A T b exp(− C / T ), where the temperature dependence term b was fixed at 1/2 to match the dependence from the theoretical formulation, the activation energy term C was set to E i (in K), and the best fit was determined by varying the parameter A .…”

Section: Shock Tube Experimentsmentioning

confidence: 99%

“…Lemal et al , recently used a CR model for high-temperature air to analyze shock tube radiation measurements. Data were acquired behind fast incident shocks (∼10–11 km/s) traveling in low-pressure (∼13 Pa) air; kinetic temperatures initially behind shock waves were ∼6 × 10 4 K, quickly falling to ∼1 × 10 4 K after less than 2 μs.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

et al. 2016

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The formation of electronically excited atomic oxygen was studied behind reflected shock waves using cavity-enhanced absorption spectroscopy. Mixtures of 1% O-Ar were shock-heated to 5400-7500 K, and two distributed-feedback diode lasers near 777.2 and 844.6 nm were used to measure time-resolved populations of atomic oxygen's S° andS° electronic states, respectively. Measurements were compared with simulated population time histories obtained using two different kinetic models that accounted for thermal nonequilibrium effects: (1) a multitemperature model and (2) a reduced collisional-radiative model. The former assumed a Boltzmann distribution of electronic energy, whereas the latter allowed for non-Boltzmann populations by treating the probed electronic states as pseudospecies and accounting for dominant electronic excitation/de-excitation processes. The effects of heavy-particle collisions were investigated and found to play a major role in the kinetics of O atom electronic excitation at the conditions studied. For the first time, rate constants (k) for O atom electronic excitation from the ground state (P) due to collisions with argon atoms were directly inferred using the reduced collisional-radiative model, k(P → S°) = 7.8 × 10T exp(-1.061 × 10K/T) ± 25% cm s and k(P → S°) = 2.5 × 10T exp(-1.105 × 10K/T) ± 25% cm s.

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Section: Shock Tube Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

et al. 2016

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“…The nonequilibrium chemical kinetics of atmospheric re-entry flows have been studied extensively since the 1960s. − A typical earth atmospheric re-entry flow, such as in the Fire II flight experiment launched within the framework of the Apollo program, can reach Mach >30 and a stagnation gas temperature above 11,000 K. ,, At such high temperatures, the constituents of air become partially ionized, and radiative heating can contribute to over 30% of the total heat flux. , In such high-speed re-entry systems, the excited atomic species, O* and N*, play important roles in radiative heating/cooling. For proper design of the thermal protection system for space vehicles, it is thus crucial to understand the fundamental kinetics of the excited atomic species at extreme temperatures.…”

Section: Introductionmentioning

confidence: 99%

Two-temperature Collisional-radiative Modeling of Partially Ionized O₂–Ar Mixtures over 8000–10,000 K Behind Reflected Shock Waves

Wang

Strand

et al. 2020

J. Phys. Chem. A

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The collisional excitation kinetics of atomic oxygen was studied behind reflected shock waves using tunable diode laser absorption spectroscopy. A test gas mixture of 1% O2/Ar was shock-heated to temperatures between 8000 and 10,000 K and pressures between 0.15 and 1 atm. The time evolution of the atomic oxygen population in the 3 s 5S0 state was monitored by laser absorption at 777.2 nm. The measured O(3 s 5S0) population revealed multistage behavior that was not observed in previous measurements over a temperature range of 5300–7200 K. To interpret the multistage behavior, a three-level collisional-radiative model for atomic oxygen excitation kinetics was developed. The model utilized two independent temperatures, that is, heavy particle translational temperature T tr and electron translational temperature T e, to describe the fundamental rate constants of atomic oxygen excitation because of collisions with heavy particles and electrons, respectively. The heavy particle excitation rate was inferred from the early stage of the measurement to be k(3P →5S0) = 3.4 × 10–27 (T/K)0.5(1.061 × 105 + 2 (T/K)) exp(−1.061 × 105 K/T) ± 50% m3 s–1. The electron impact excitation rate constant of oxygen, electron impact, and heavy particle impact ionization rate constants of Argon were modified in the model to match the experimental population time histories. The modified rate parameters are also reported for the temperature range explored in the current study.

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“…A variety of detailed chemistry models are available in the literature [2,[48][49][50][51]. Most of them are hybrid models combining a state-to-state approach, for part of the internal energy levels populations, together with a multitemperature approach, assuming that the rest of the energy level populations follow Boltzmann distributions at their relevant temperature.…”

Section: Mixture Description and Chemical Mechanismmentioning

confidence: 99%

Energy Accommodation Coefficient Calculation Methodology Using State-to-State Catalysis Applied to Hypersonic Flows

2020

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The interplay of a gas-surface interaction and thermal nonequilibrium is still an open problem in aerothermodynamics. In the case of reusable thermal protection systems, it is unclear how much of the recombination energy is stored internally in the molecules produced by surface catalytic reactions, potentially leading to nonequilibrium between their translational and internal energy modes. A methodology is developed to calculate the energy accommodation coefficient using a rovibrational state-to-state chemical mechanism for a nitrogen mixture coupled with a generalized form of the catalytic recombination coefficient. The flow around a spherical body is simulated in hypersonic conditions, allowing study of the amount of energy deposited on the surface and stored in the recombining molecules. Internal energy quenching into translational energy is found, which is a phenomenon also observed experimentally, keeping the total energy transferred to the surface overall constant. The methodology developed for the application of a state-to-state model in the computational fluid dynamics framework coupled with catalysis is generic and applicable to a variety of other similar mechanisms.

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Air Collisional-Radiative Modeling with Heavy-Particle Impact Excitation Processes

Cited by 15 publications

References 65 publications

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Two-temperature Collisional-radiative Modeling of Partially Ionized O₂–Ar Mixtures over 8000–10,000 K Behind Reflected Shock Waves

Energy Accommodation Coefficient Calculation Methodology Using State-to-State Catalysis Applied to Hypersonic Flows

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Air Collisional-Radiative Modeling with Heavy-Particle Impact Excitation Processes

Cited by 15 publications

References 65 publications

Kinetics of Excited Oxygen Formation in Shock-Heated O2–Ar Mixtures

Kinetics of Excited Oxygen Formation in Shock-Heated O2–Ar Mixtures

Two-temperature Collisional-radiative Modeling of Partially Ionized O2–Ar Mixtures over 8000–10,000 K Behind Reflected Shock Waves

Energy Accommodation Coefficient Calculation Methodology Using State-to-State Catalysis Applied to Hypersonic Flows

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Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Two-temperature Collisional-radiative Modeling of Partially Ionized O₂–Ar Mixtures over 8000–10,000 K Behind Reflected Shock Waves