Effects of inlet air temperature and mass flow rate on the performance of a liquid kerosene/air rotating detonation ramjet combustor

Abstract

A systematic numerical study of a liquid kerosene/air rotating detonation ramjet combustor under high mach number conditions was conducted using the Euler–Lagrange method. The effects of inlet air temperature and mass flow rate on two-phase flow distribution, detonation-wave propagation, and combustor performance were analyzed. Results show that under non-premixed injection, the detonation wave couples positively with atomization and mixing, while two additional modes—parasitic combustion (autoignition ahead of the detonation wave front) and commensal combustion (secondary burning of unreacted fuel)—reduce the detonation contribution and degrade performance compared with gaseous premixed models. The total inlet air temperature has a significant influence on the detonation propagation mode. At lower temperatures, insufficient reactant reactivity results in a single detonation mode with weaker intensity. As the temperature increases, intensified parasitic combustion may trigger new detonation waves, leading to a double detonation mode with two co-rotating waves. At excessively high temperatures, large-scale parasitic combustion occurs ahead of the detonation front, causing wave decoupling and unstable propagation. Thus, combustor performance does not monotonically increase with temperature; instead, there exists an optimal temperature that balances the proportions of parasitic and commensal combustion to achieve maximum performance. Moreover, reducing the outlet contraction ratio effectively suppresses parasitic combustion and prevents unstable detonation modes. Increasing air mass flow enhances reactant filling and resistance to backflow, raises combustor pressure, enlarges detonation-wave dimensions, and increases both detonation contribution and volumetric heat release rate, thereby continuously improving thrust and specific impulse.