Numerical study on turbulent combustion in high Mach number scram-jet engine considering thermal non-equilibrium effect

During hypersonic flight, the temperature inside the boundary layer rapidly increases with the increase of Mach number, leading to the excitation of molecular vibration and electron energy. Gaseous molecules undergo dissociation or even ionization, making the assumption of complete gas calorimetry invalid, and thereby affecting the characteristics of the scram-jet engine. The turbulent combustion in the scram-jet engine under the Ma 12 flight condition is numerically studied via a thermodynamic equilibrium model and the Park's dual temperature non-equilibrium model where the high-temperature thermal non-equilibrium effects are considered. The results indicate that compared to the equilibrium case, the non-equilibrium effect causes the position of the shock wave trains to shift forward, and the increase of the peak pressure between shock waves. This is more significant for the frozen flow field. The temperature field T_tr in the non-equilibrium case is not significantly different from that of the equilibrium case, and the thermodynamic non-equilibrium effect slightly increases T_tr. The combustion efficiency at the outlet section is lower in the non-equilibrium case, and the thermodynamic non-equilibrium effect slightly weakens the intensity of the reactions.