Theory and validation of the physically consistent coupled vibration-chemistry-vibration model

Knab, O.; Fruehauf, H.-H.; Messerschmid, Ernst

doi:10.2514/3.649

Cited by 146 publications

(62 citation statements)

References 14 publications

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“…Although the vibrational-vibrational (V-V) energy redistribution is known to play only a secondary role in vibrational energy exchange, the multi-vibrational temperature option has been retained to allow a consistent coupling between dsmcFoam and hy2Foam. The formulation that has been implemented to account for V-V energy transfer is the one of Knab et al [25,26]. The source term designated by Q m, V−V may be written as (18) where N A is the Avogadro number, R is the universal gas constant, and P m,l represents the assessed exchange probability whose recommended value is a constant equal to 10 −2 [27].…”

Section: Two-temperature Modelmentioning

confidence: 99%

A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part One: Zero-Dimensional Analysis

et al. 2016

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A two-temperature CFD (computational fluid dynamics) solver is a prerequisite to any spacecraft re-entry numerical study that aims at producing results with a satisfactory level of accuracy within realistic timescales. In this respect, a new two-temperature CFD solver, hy2Foam, has been developed within the framework of the open-source CFD platform OpenFOAM for the prediction of hypersonic reacting flows. This solver makes the distinct juncture between the trans-rotational and multiple vibrational-electronic temperatures. hy2Foam has the capability to model vibrational-translational and vibrational-vibrational energy exchanges in an eleven-species air mixture. It makes use of either the Park TTv model or the coupled vibration-dissociation-vibration (CVDV) model to handle chemistry-vibration coupling and it can simulate flows with or without electronic energy. Verification of the code for various zero-dimensional adiabatic heat baths of progressive complexity has been carried out. hy2Foam has been shown to produce results in good agreement with those given by the CFD code LeMANS (The Michigan Aerothermodynamic Navier-Stokes solver) and previously published data. A comparison is also performed with the open-source DSMC (direct simulation Monte Carlo) code dsmcFoam. It has been demonstrated that the use of the CVDV model and rates derived from Quantum-Kinetic theory promote a satisfactory consistency between the CFD and DSMC chemistry modules.

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Section: Two-temperature Modelmentioning

confidence: 99%

A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part One: Zero-Dimensional Analysis

et al. 2016

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“…• Model (iv): Another approach to examine the effect of vibrational non-equilibrium is the physically consistent CVCV model, which is derived on the assumptions of the T v -Boltzmann populated vibrational energy mode and truncated harmonic oscillator (Knab et al, 1995). In this model, the chemical reaction rate is modified by an efficiency function, φ(T tr , T v ):…”

Section: Physical Models and Methodsmentioning

confidence: 99%

“…The coefficient α, which determines the fraction of required energy contributed by the translational energy, is selected as 0.8, and U ¼ E d =ð5RÞ as assessed in Knab et al (1995), Koo et al (2015), and Voelkel et al (2015). QðT; EÞ¼ …”

Section: Physical Models and Methodsmentioning

confidence: 99%

“…Quantitative comparisons of halfreaction thickness and cell widths from thermodynamic equilibrium cases to thermodynamic non-equilibrium cases are discussed in detail to examine the effect of vibrational non-equilibrium. The interactions between vibrational non-equilibrium and chemical reactions are treated with Park's two-temperature model (1989) and the more recent coupled-vibration-chemistryvibration (CVCV) model (Knab et al, 1995;Koo et al, 2015;Voelkel et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Assessment of Vibrational Non-Equilibrium Effect on Detonation Cell Size

Shi

Shen

Zhang

et al. 2016

Combustion Science and Technology

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To resolve the discrepancy between the numerical detonation cell size and experimental observations, simulations are conducted with a detailed thermochemical reaction model for a premixed argondiluted hydrogen-oxygen mixture. Four different scenarios are considered: (i) The whole system is in thermodynamic equilibrium; (ii) the vibrational relaxation is considered and the translational-rotational temperature is used as the dominant temperature of the chemical reactions; (iii) the same non-equilibrium effect as in the second scenario is used along with Park's two-temperature model to account for the effect of vibrational temperature on chemical reaction rates; and (iv) a more physically consistent vibration-chemistry-vibration coupling model is adopted. The simulated detonation cell widths for the first and second scenarios are significantly lower than the experimental measurements, whereas reasonable agreement is observed for the third and fourth scenarios. These results confirm that the involvement of vibrational relaxation in the chemical reactions is an important mechanism in gaseous detonation. ARTICLE HISTORY

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“…Another approach is based on the generalizations of the Treanor-Marrone model to exchange reactions suggested in Refs. Aliat (2008); Knab (1996); Knab et al (1995); Seror et al (1997). These models can be used for more general cases, but the theoretical expressions for the rate coefficients contain additional parameters, which should be validated using experimental data.…”

Section: The Right Hand Sides Of Eqs (66) R (0)mentioning

confidence: 99%