Large Eddy Simulations of Rotating Detonations in Non-Premixed H ₂ -Air Annular Combustor

High fidelity Large Eddy Simulations (LES) are performed on a non-premixed hydrogen-air annular rotating detonation combustor. The simulations utilize a 22-step hydrogen-air reaction mechanism and an existing flow solver that is optimized for high-speed reacting flows. The selected combustor, designed by the US Air Force Research Laboratory (AFRL), has been extensively studied experimentally across various configurations and operating conditions. In this study, a specific geometrical configuration is examined, with variations in the mass flow rate while maintaining a global equivalence ratio of ϕ = 1. Two mass flow rates are investigated. After initiation and an unsteady transition phase, the detonation waves settle into a stable rotational mode. The concerned cases predict either one or two co-rotating waves, with higher flow rates leading to an increased number of waves. The LES model successfully captures key characteristics of rotating detonation waves, and its predictive capability is quantitatively assessed using available experimental data. The computed time-averaged chamber pressures closely align with experimental values and patterns; the simulated detonation wave frequencies fall into similar ranges as those clocked in the AFRL hardware firings. The time-resolved LES data reveals insights into mixing and combustion phenomena within a rotating detonation combustion, ranging from pre- to post-wave. The dynamics of the propagating wave(s) and its interactions with the surrounding flow field are analyzed, the most significant of which include sharp temperature and pressure rises, volume expansion, fuel suppression and vorticity traces, at and right behind the detonation front.