Numerical study on the transient dynamics and film cooling effect in a non-premixed cylindrical rotating detonation engine

This study presents a three-dimensional numerical analysis of a cylindrical rotating detonation engine (RDE) utilizing a non-premixed injection scheme, in which the gaseous fuel is injected from the outer periphery toward the center through a slit-orifice injection system. The investigation explores the ignition process, transient behavior, and the structure of the rotating detonation wave (RDW) under varying mass flow rates. Additionally, the influence of the film cooling jets is analyzed in the current non-premixed RDE, where three different types of complex-shaped film cooling holes are considered and compared. At a low air flow rate of 100 g/s, the detonation flow field exhibits frequent combustion instabilities, including RDW intensity attenuation, quenching, and re-ignition due to self-ignition in the fuel refill region. These instabilities result in transitions between single-wave, dual-wave, and quenching states. At an air flow rate of 200 g/s, a stable single-wave mode is observed; however, the RDW shape fluctuates, alternating between elevated, stratified, inclined, and diminished wave front patterns. As the air flow increases to 300 g/s and 400 g/s, the RDW stabilizes into a dual high-pressure region with an approximate 40° forward inclination. When film cooling is introduced, although the RDW's structure remains stable, the cooling air jet alters fuel mixing, leading to low hydrogen mass fractions and affecting local equivalence ratios. © 2024 Author(s).