On the role of back-propagating pressure suppression in enhancing the pressure-gain performance of quasi-2D rotating detonation engines

The total pressure gain (PG) performance of quasi-2D rotating detonation engines (RDEs) is numerically investigated to address the critical gap in quantifying the effects of back-propagating pressure suppression. In this study, a quasi-2D RDE model with an expansion ratio A_e is developed by adopting a quasi-1D assumption to simplify radial features. An abstract check valve model is further established to simulate various flow channel configurations, with the suppression capability parameterized by a tunable backflow check strength α_b. By systematically evaluating the flow field under varying A_e and α_b, this study reveals the constraints between them; specifically, achieving positive PG demands an expansion ratio of A_e<3.336, which can only be sustained without inlet blocking when α_b>51.1. Furthermore, a specific shock structure, termed the cut-off normal shock wave, is identified as the dominant aerodynamic mechanism responsible for total pressure loss. Finally, a general PG criterion based on the equivalent inlet Mach number is derived. Under baseline operating parameters, this criterion indicates that positive PG is achieved within a Mach number range of 0.177 to 2.749. Further parametric analyses demonstrate that stoichiometric hydrogen/air mixtures and a lower inlet total temperature facilitate the achievement of positive PG. This study provides theoretical guidance for enhancing PG in RDEs.