A parametric three-dimensional study of combustion modes and thrust performance in rotating detonation engine with aerospike nozzle

Previous research has indicated that under certain inflow conditions, the throat ratio of the back nozzle can cause a transition to the combustion mode of rotating detonation engines (RDEs), consequently affecting thrust performance, but the specific conditions for the occurrence and underlying mechanisms of this transition are unclear. A three-dimensional numerical study is conducted to investigate the effects of inflow total pressures, nozzle throat ratio, and combustion chamber width to provide a comprehensive understanding of the effects of various inflow conditions, nozzle, and combustion chamber configurations on the combustion modes and thrust performance of RDEs with back nozzle. The results show that reducing the nozzle throat ratio leads to a transition from a stable single wave to an unstable multi-detonation wave mode in RDEs; conversely, increasing the inflow pressure can re-stabilize the detonation waves but may lead to quenching under excessively high-pressure conditions. Additionally, decreasing the combustion chamber thickness broadens the stable mode range under operating conditions. The underlying reason is analyzed with the flow structure in the combustion chamber, indicating that the pressure variation caused by shock waves and three-dimensional effects are the main reasons, causing the transition of combustion modes. The propulsion performance is analyzed, revealing that increasing pressure and chamber width lead to enhanced thrust, with minimal changes in specific impulse; meanwhile, a reduced throat ratio leads to a nonlinear trend in thrust and specific impulse caused by the reflected shock waves.