Energy transfer study of N₂(¹∑⁺ _g)-N₂(¹∑⁺ _g) and N₂(¹∑⁺ _g)-N(⁴S_u) interactions by using rovibrational state-to-state model

A rovibrational collisional model is developed to study energy transfer N₂(¹∑⁺ _g) molecules interacting with N₂(¹∑⁺ _g) molecules and N(⁴S_u) atoms in an ideal isochoric and isothermal chemical reactor. Cold nitrogen molecules at room temperature, are suddenly heated by several thousand degrees Kelvin, driving the gas toward a strong non-equilibrium condition. The evolution of the population densities is determined via the numerical solution of the master equations for temperatures ranging from 1,000 to 50,000 [K]. The elementary reaction rate coefficients are taken from the newly developed ab-initio database of the NASA Ames Research Center. The analysis of the results of the master equation allows for the shape of the internal distribution function to be characterized without any a priori assumptions. The departures of the internal distribution from the equilibrium Maxwell-Boltzmann distribution are discussed for operating conditions of encountered in hypersonic applications. Finally, in an attempt to validate the results of the calculations, rotational-translational (RT), vibrational-translational (VT) relaxation times and macroscopic dissociation rate coefficients are extracted from the results of the master equation and are compared with the available experimental data.