High Fidelity Simulations of a Non-Premixed Rotating Detonation Engine

Computational fluid dynamics tools have the potential to enhance the understanding of rotating detonation engines and aid future development of this technology. Realistic rotating detonation engine concepts utilize separate fuel and air injection and are not perfectly premixed. Therefore, the ability to accurately capture the fuel-air mixing and subsequent heat release using computational methods is important. This paper presents high fidelity simulations of a representative non-premixed RDE studied at the Air Force Research Laboratory. An attempt is made to evaluate the predictive capabilities of the computational approach through comparison to experimental data. Two cases are simulated, with different fuel and air mass flow rates. Both cases have a unity overall stoichiometric ratio. Computational data compares well to experimental measurements of the mean axial pressure distribution in the combustor annulus, with both quantitative values and trends well captured. However the simulations over predict both the detonation wave frequency and the fuel and air plenum pressures. It is suggested that this over prediction of plenum pressures may impact fuel-air mixing and subsequently the detonation wave speed. The combustion efficiency is found to be higher for the lowest mass flow rate case, but a more significant fraction of the heat release occurs at lower pressures in this simulation. Evidence of flame holding on the inner diameter of the combustor annulus is identified, due to the presence of a re-circulation zone in this region.