Large eddy simulation of a supersonic inlet turbine in a rotating detonation engine

A rotating detonation combustor (RDC) is an innovative technology with the potential to improve the efficiency of modern gas turbines. However, the highly unsteady and transonic flows generated by RDCs require advanced turbine designs, such as supersonic inlet turbines, to fully realize their benefits. This paper presents the first large eddy simulation of a complete supersonic turbine stage operating with RDC-representative inlet conditions. The investigation begins by evaluating the accuracy of Reynolds-averaged Navier-Stokes (RANS) simulations, widely employed for designing and optimizing supersonic inlet turbines. The strengths and limitations of RANS in capturing the complex flow physics of such systems are revealed. Aerodynamic losses within the turbine are quantified and compared with predictions from established mean-line design loss models. An entropy decomposition framework is then applied to uncover the dominant physical mechanisms of entropy generation and to identify regions of peak entropy production. The impact of RDC wave propagation through the stator and rotor blade rows is analyzed through phase-phase diagrams of phase-locked-averaged quantities, revealing key unsteady flow interactions. Additionally, the dominant modes characterizing the flow separation on the stator's suction side are detected with dynamic mode decomposition, and an accurate reduced-order model is developed with the state-of-the-art shallow recurrent decoder neural network. This work provides critical insights into the aerodynamic performance, loss mechanisms, and unsteady flow phenomena of supersonic inlet turbines in a rotating detonation engine (RDE). These findings pave the way for the practical implementation and continued advancement of RDE-integrated turbine technologies.