Eucken correction in high-temperature gases with electronic excitation

Истомин, В. А.; Кустова, Е. В.; Mekhonoshina, M.

doi:10.1063/1.4874257

Cited by 22 publications

(7 citation statements)

References 29 publications

(34 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under this assumption, no internal heat conductivity and bulk viscosity coefficients appear for atomic species, both neutral and ionized, which can cause the loss of accuracy in the transport terms evaluation. Rigorous kinetic theory approaches for transport processes in chemically non-equilibrium ionized flows with electronic degrees of freedom have been proposed recently on the basis of the Chapman-Enskog [18][19][20][21][22][23] and Grad 24,25 methods. Detailed analysis of thermal conductivity coefficients in electronically excited gases shows an important contribution of electronic levels to the thermal conductivity of both near equilibrium and strongly chemically non-equilibrium plasmas.…”

mentioning

confidence: 99%

Transport coefficients and heat fluxes in non-equilibrium high-temperature flows with electronic excitation

Истомин

Кустова

2017

Physics of Plasmas

Self Cite

View full text Add to dashboard Cite

The influence of electronic excitation on transport processes in non-equilibrium high-temperature ionized mixture flows is studied. Two five-component mixtures, N 2 =N þ 2 =N=N þ =e À and O 2 =O þ 2 =O=O þ =e À , are considered taking into account the electronic degrees of freedom for atomic species as well as the rotational-vibrational-electronic degrees of freedom for molecular species, both neutral and ionized. Using the modified Chapman-Enskog method, the transport coefficients (thermal conductivity, shear viscosity and bulk viscosity, diffusion and thermal diffusion) are calculated in the temperature range 500-50 000 K. Thermal conductivity and bulk viscosity coefficients are strongly affected by electronic states, especially for neutral atomic species. Shear viscosity, diffusion, and thermal diffusion coefficients are not sensible to electronic excitation if the size of excited states is assumed to be constant. The limits of applicability for the Stokes relation are discussed; at high temperatures, this relation is violated not only for molecular species but also for electronically excited atomic gases. Two test cases of strongly non-equilibrium flows behind plane shock waves corresponding to the spacecraft re-entry (Hermes and Fire II) are simulated numerically. Fluid-dynamic variables and heat fluxes are evaluated in gases with electronic excitation. In inviscid flows without chemical-radiative coupling, the flow-field is weakly affected by electronic states; however, in viscous flows, their influence can be more important, in particular, on the convective heat flux. The contribution of different dissipative processes to the heat transfer is evaluated as well as the effect of reaction rate coefficients. The competition of diffusion and heat conduction processes reduces the overall effect of electronic excitation on the convective heating, especially for the Fire II test case. It is shown that reliable models of chemical reaction rates are of great importance for accurate predictions of the fluid dynamic variables and heat fluxes. Published by AIP Publishing. [http://dx

show abstract

mentioning

confidence: 99%

Transport coefficients and heat fluxes in non-equilibrium high-temperature flows with electronic excitation

Истомин

Кустова

2017

Physics of Plasmas

Self Cite

View full text Add to dashboard Cite

show abstract

“…[22]; in Ref. [23] the heat conductivity of electronically excited atoms and molecules under non-equilibrium conditions was studied. It was found that at high temperature the size of atoms influences significantly the collision integrals.…”

Section: Introductionmentioning

confidence: 99%

Effect of molecular diameters on state-to-state transport properties: The shear viscosity coefficient

Кустова

Kremer

2015

Chemical Physics Letters

View full text Add to dashboard Cite

“…It is known that collision integrals may considerably increase with the rise of principle quantum number [1,11,13]. It is however worth mentioning that implementation of the Slater's approach (18) yields over-predicted transport cross-section and does not account for the resonant processes of excitation and chargeexchange in collisions involving excited atoms or ion-parent atoms [11,28].…”

Section: Transport Coefficientsmentioning

confidence: 99%

“…The objective of the present study is to generalize our previous one-temperature models of high-temperature reacting flows with electronic excitation [10,[12][13][14][15] by including state-to-state kinetics of electronic levels and state-dependent transport coefficients. While the state-to-state model has been widely used in simulations of vibrationally excited flows (see references in [16,11]), its implementation for gases with electronic excitation is just starting [17,18,11,19,20].…”

Section: Introductionmentioning

confidence: 99%

State-specific transport properties of partially ionized flows of electronically excited atomic gases

Истомин

Кустова

2017

Chemical Physics

View full text Add to dashboard Cite

a b s t r a c tState-to-state approach for theoretical study of transport properties in atomic gases with excited electronic degrees of freedom of both neutral and ionized species is developed. The dependence of atomic radius on the electronic configuration of excited atoms is taken into account in the transport algorithm. Different cutoff criteria for increasing atomic radius are discussed and the limits of applicability for these criteria are evaluated. The validity of a Slater-like model for the calculation of state-resolved transport coefficients in neutral and ionized atomic gases is shown. For ionized flows, a method of evaluation for effective cross-sections of resonant charge-transfer collisions is suggested. Accurate kinetic theory algorithms for modelling the state-specific transport properties are applied for the prediction of transport coefficients in shock heated flows. Based on the numerical observations, different distributions over electronic states behind the shock front are considered. For the Boltzmann-like distributions at temperatures greater than 14,000 K, an important effect of electronic excitation on the partial thermal conductivity and viscosity coefficients is found for both neutral and ionized atomic gases: increasing radius of excited atoms causes a strong decrease in these transport coefficients. Similarly, the presence of electronically excited states with increased atomic radii leads to reduced diffusion coefficients. Nevertheless the overall impact of increasing effective cross-sections on the transport properties just behind the shock front under hypersonic reentry conditions is found to be minor since the populations of high-lying electronic energy levels behind the shock waves are low.

show abstract

Eucken correction in high-temperature gases with electronic excitation

Cited by 22 publications

References 29 publications

Transport coefficients and heat fluxes in non-equilibrium high-temperature flows with electronic excitation

Transport coefficients and heat fluxes in non-equilibrium high-temperature flows with electronic excitation

Effect of molecular diameters on state-to-state transport properties: The shear viscosity coefficient

State-specific transport properties of partially ionized flows of electronically excited atomic gases

Contact Info

Product

Resources

About