Arrays of radiative transition probabilities for plasmas

Silva, M. Lino da; Dudeck, Michel

doi:10.1016/j.jqsrt.2006.02.018

Cited by 43 publications

(21 citation statements)

References 68 publications

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“…Therefore, a more accurate calculation of the vibrational level energies is carried through the reconstruction of potential curves according to the Rydberg-Klynning-Rees (RKR) method, and the resolution of the radial Schrödinger equation for this potential curve, as described in another work [42]. The predicted maximum vibrational level of N 2 corresponds in this case to v max 59 instead of v max 45 predicted when the polynomial expansion of Eq.…”

Section: Improvements To the Fho Modelmentioning

confidence: 99%

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State-Resolved Dissociation Rates for Extremely Nonequilibrium Atmospheric Entries

Silva

Guerra

Loureiro

2007

Journal of Thermophysics and Heat Transfer

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This paper presents the application of the forced harmonic oscillator method to the simulation of state-resolved dissociation processes behind high-temperature shock waves typical of atmospheric reentries. Improvements have been brought to the model, considering a more precise method for the calculation of the different vibrational level energies, therefore increasing the accuracy of the predicted transition probabilities between higher vibrational levels close and above the dissociation limit. The model has been validated against data issued from recent experiments, as well as data issued from semiclassical trajectory calculations for collisions between different species. A good overall agreement is achieved against such other data. A database of reaction rates has been constructed with the purpose of simulating shock-heated nitrogen flows. Dissociation processes behind a shock wave have been simulated for different postshock translational temperatures. At lower temperatures, the well-known ladder-climbing phenomenon is the main dissociation channel behind a shock wave, with dissociation occurring for transitions from the vibrational levels close to the dissociation limit. At higher temperatures, transitions between the different vibrational levels of nitrogen become roughly equiprobable, and the overall range of bound vibrational levels contributes to the dissociation. Nomenclature C k ij = transformation matrix C p = specific heat at constant pressure, J=kg=K C v = specific heat at constant volume, J=kg=K E = level energy, Hz E m = Morse potential well, J h = enthalpy, J=kg J s = Bessel function k B = Boltzmann constant, 1:3806505 10 23 J=K kT = thermal reaction rate, cm 3 =s M = Mach number m = mass, kg m= mass parameter, m AB m C =m AB m C or m AB m CD =m AB m CD P = probability r = internuclear distance, m S VT = vibration-translation steric factor, 4=9 S VV = vibration-vibration steric factor, 1=27 T = macroscopic temperature, K T r = rotational temperature, K T tr = translational temperature, K T tr-r = translational-rotational temperature, K T v = vibrational temperature, K t = time, s Vr = intermolecular potential, J V-T = vibration-translation processes V-V-T = vibration-vibration-translation processes v = vibrational level v = velocity, m=s v = averaged collision velocity, m=s Z = gas-kinetic collisional frequency, Hz = repulsive potential parameter, m 1 = heat capacity ration, C p =C v = mass parameter, m A =m A m B "= two-state first-order V-T transition probability, P1 ! 0 = mass parameter, m A m B =m A m B = two-state first-order V-V-T transition probability, 4P1; 0 ! 0; 1 1=2 = generalized two-state first-order V-V-T transition probability = collision cross section, m 2 ! = vibrational transition frequency, Hz ! e = harmonic oscillator energy, Hz ! e x e = first-order anharmonic oscillator energy, Hz Subscripts f = final vibrational quantum number i = initial vibrational quantum number max = maximum vibrational level before dissociation qbound = vibrational level above the dissociation limit tr =...

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Section: Improvements To the Fho Modelmentioning

confidence: 99%

“…Furthermore, Eq. (11) also provides erroneous values for the level energies from sensibly v 40 [42]. This restriction has prevented higher quasi-bound levels to be considered in other works using the FHO model [40].…”

Section: Simulation Of Dissociation Processes In High-energy Nitrmentioning

confidence: 99%

State-Resolved Dissociation Rates for Extremely Nonequilibrium Atmospheric Entries

Silva

Guerra

Loureiro

2007

Journal of Thermophysics and Heat Transfer

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“…All of the studied radiation codes used spectroscopic data from Laux's work [19]. In this work, spectroscopic data for the red and violet bands of CN have been taken from Laux's work [19] and data for the CO (4) band have been taken from the work of Silva and Dudeck [22]. Molecular radiation is marked by the presence of a large number of rovibrational bands, with each band having large numbers of rotational lines.…”

Section: Radiation Modelsmentioning

confidence: 99%

“…(6), is approximated by assuming that the upper state population n l 0 is related to the lower state population n l 0 0 using a Boltzmann distribution at the vibrational temperature T v . This leads to 22) and the absorption cross section is defined as:…”

Section: Database Of Emission-weighted Full-spectrum K-distributionsmentioning

confidence: 99%

Modeling of Radiative Heat Transfer in Carbonaceous Atmospheres Using k-Distribution Models

Bansal

Modest

2013

Journal of Thermophysics and Heat Transfer

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Full-spectrum correlated k-distribution models are presented for bands of CN and CO for applications relevant to entry into atmospheres of Titan, Mars, Venus and flows over an ablating heat shield. A new emission-weighted fullspectrum k-distribution model is proposed as an improvement over the more popular Planck function-weighted fullspectrum k-distribution model. In the new reordering scheme, emission coefficient is used as the weight instead of the Planck-function. To exploit the full potential of the k-distribution method databasing schemes for k distributions are discussed and CPU time studies are presented. The accuracy of the new model and the database is demonstrated by solving the radiative transfer equation for two-cell problems and stagnation line flowfields of Titan's Huygens spacecraft and a spacecraft entering into the Martian atmosphere.

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“…Recent reviews of molecular band system data for a CO 2 -N 2 gas [114][115][116][117] provide valuable insight into the uncertainties for many of the bands systems resulting from diatomic ablation products. Comparisons between experimental measurements and various predictions for the oscillator strengths for the C 2 and CO molecules are made in these papers.…”

Section: Molecular Band Systems For Ablation Productsmentioning

confidence: 99%

Assessment of Radiative Heating Uncertainty for Hyperbolic Earth Entry

Johnston

Mazaheri

Gnoffo

et al. 2011

42nd AIAA Thermophysics Conference

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This paper investigates the shock-layer radiative heating uncertainty for hyperbolic Earth entry, with the main focus being a Mars return. In Part I of this work, a baseline simulation approach involving the LAURA Navier-Stokes code with coupled ablation and radiation is presented, with the HARA radiation code being used for the radiation predictions. Flight cases representative of peak-heating Mars or asteroid return are defined and the strong influence of coupled ablation and radiation on their aerothermodynamic environments are shown. Structural uncertainties inherent in the baseline simulations are identified, with turbulence modeling, precursor absorption, grid convergence, and radiation transport uncertainties combining for a +34% and −24% structural uncertainty on the radiative heating. A parametric uncertainty analysis, which assumes interval uncertainties, is presented. This analysis accounts for uncertainties in the radiation models as well as heat of formation uncertainties in the flowfield model. Discussions and references are provided to support the uncertainty range chosen for each parameter. A parametric uncertainty of +47.3% and −28.3% is computed for the stagnation-point radiative heating for the 15 km/s Mars-return case. A breakdown of the largest individual uncertainty contributors is presented, which includes C3 Swings cross-section, photoionization edge shift, and Opacity Project atomic lines. Combining the structural and parametric uncertainty components results in a total uncertainty of +81.3% and −52.3% for the Mars-return case.In Part II, the computational technique and uncertainty analysis presented in Part I are applied to 1960s era shock-tube and constricted-arc experimental cases. It is shown that experiments contain shock layer temperatures and radiative flux values relevant to the Mars-return cases of present interest. Comparisons between the predictions and measurements, accounting for the uncertainty in both, are made for a range of experiments. A measure of comparison quality is defined, which consists of the percent overlap of the predicted uncertainty bar with the corresponding measurement uncertainty bar.

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Arrays of radiative transition probabilities for plasmas

Cited by 43 publications

References 68 publications

State-Resolved Dissociation Rates for Extremely Nonequilibrium Atmospheric Entries

State-Resolved Dissociation Rates for Extremely Nonequilibrium Atmospheric Entries

Modeling of Radiative Heat Transfer in Carbonaceous Atmospheres Using k-Distribution Models

Assessment of Radiative Heating Uncertainty for Hyperbolic Earth Entry

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