On the non-equilibrium kinetics and heat transfer in nozzle flows

Different Approaches for Modelling of Heat Transfer in Non-Equilibrium Reacting Gas Flows

“…On the contrary, in a nozzle flow, at low levels difference between state-to-state and quasi-stationary distributions is negligible and becomes significant at intermediate and high levels. As shown in Kustova, Nagnibeda, Alexandrova & Chikhaoui (2002), contribution to the heat flux mainly is due to low vibrational levels, therefore difference between heat flux values obtained in different approaches occurs small. Thereby, to calculate the macroscopic parameters and to estimate the heat transfer in nozzle flows, the multi-temperature approach providing a satisfactory accuracy can be used.…”

“…Then the obtained non-equilibrium distributions were used to calculate the transport coefficients, diffusion velocities, and heat fluxes on the basis of the accurate formulae of the kinetic theory. This approach was used for the evaluation of transport properties in the flows of non-equilibrium reacting mixtures of air components behind shock waves Chikhaoui et al (2000); , in the nozzle expansion Capitelli et al (2002); Kustova, Nagnibeda, Alexandrova & Chikhaoui (2002), in the hypersonic boundary layer Armenise et al (2006;; Kustova, Nagnibeda, Armenise & Capitelli (2002) (see also ). Below, we present some results of these applications concerning heat transfer in particular flows studied using the state-to-state, multi-temperature and one-temperature models.…”

“…The model presented in this section gives a principle possibility to take into account the state-to-state transport coefficients in numerical simulations of viscous conducting gas flows under the conditions of strong vibrational and chemical non-equilibrium. The influence of state-to-state vibrational and chemical kinetics on the dissipative processes was studied using this model in the flows of binary mixtures of air components behind shock waves and in the nozzle expansion of binary mixtures Kustova, Nagnibeda, Alexandrova & Chikhaoui (2002) and 5-component air mixture Capitelli et al (2002). However, even taking into account proposed simplifications of transport coefficients mentioned above, the problem of implementation of the state-to-state model of transport properties in numerical fluid dynamic codes for the flows of multi-component reacting mixtures remains time consuming and numerically expensive for applications particularly if many test cases should be considered.…”

“…The proposed multi-temperature model was applied in Chikhaoui et al (2000) for the simulation of gas-dynamic parameters, transport coefficients and heat fluxes in non-equilibrium reacting flows of 5-component air mixture behind shock waves. The flows of binary mixtures of air components behind shock waves are studied in and in nozzles in Kustova, Nagnibeda, Alexandrova & Chikhaoui (2002).…”

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

“…Whereas diffusion of excited vibrational species was recently studied in several papers [48][49][50][51]46], investigation of diffusion and thermal diffusion of electronically excited gases, especially atomic ones, is still an open problem. Calculation of state-resolved diffusion coefficients is of importance for predictions of the heat flux (7) and diffusion velocity (6) near the surface of reentry spacecraft.…”