Influence de la relaxation de vibration sur un ecoulement gazeux en tuyere

Thermal relaxation between different intermolecular energies disturbs macroscopic features of gas flows. Expansion of a gas, such as CO ₂, is studied in a nozzle where the time of transit is of the same order of magnitude as the vibrational relaxation time. The solution of the axi-symmetrical two-dimensional flow field yields the specification of the position and shift of the singular surface from equilibrium to frozen flow. The disequilibration of the vibrational energy is shown to be important at the sonic throat. The discharge coefficient due to thermal relaxation was computed and an analytical expression for its evaluation is proposed; the results are shown to compare favorably with experimental measurements.