Thermochemical non-equilibrium effects on hypersonic wavecatcher intake at Mach 12

The thermal and chemical non-equilibrium effects on the flow structures and performance of a hypersonic inward-turning intake, for the airbreathing scramjet propulsion, are numerically studied at Mach 12. Three gas models of 1) thermally perfect gas (TPG), 2) chemical non-equilibrium gas (CNEG), and 3) thermochemical non-equilibrium gas (TCNEG), are performed. The influence of wall temperatures is analyzed, with isothermal and adiabatic wall conditions. Wall temperature has a significant effect on the mass capture coefficient, dropping by almost 6% from Tw = 300 K to adiabatic cases. The dissociation of air occurs mainly in the boundary layer near the wall. As the wall temperature decreases, so does the degree of dissociation inside the intake. For adiabatic cases, the results show that the degree of dissociation with TCNEG model is higher than that of the CNEG model. The degree of oxygen dissociation with TCNEG model reaches 54.0% in the symmetry plane, which is 6.3% higher than the value predicted by CNEG model. For the isothermal case at Tw = 2000 K, only a few dissociated oxygen atoms are observed in the isolator with TCNEG and CNEG model, and it is much less than that of adiabatic case. It is suggested that the thermochemical non-equilibrium effect is significant for a Mach 12 intake at adiabatic wall conditions.