Numerical Investigation of Ignition Strategies in Non-Premixed Rotating Detonation Engines

This thesis investigates the modeling and analysis of non-premixed Rotating Detonation Engines (RDE) using the commercial CFD software ANSYS Fluent. While the main focus was given to the numerical ignition strategies for initiating combustion reactions through the high-speed diffusing fuel-oxidizer mixture within the annular rotating detonation combustor, an extensive study of effective meshing and accurate high-fidelity 3D reactive URANS simulation methodologies was also pursued. The manuscript is organized into several integral sections, commencing with an introduction to detonation physics, followed by an exploration of RDE thermodynamics and the fundamental equations governing fluid dynamics and combustion processes. A comprehensive review of the current state of the art in RDE simulations is presented. Building on this, a two-dimensional unwrapped model is developed and tested with different numerical approaches to identify the most effective strategy. The engine geometry computational domain is meticulously discretized using a structured mesh generated in ANSYS ICEM CFD. A preliminary cold-flow simulation is then performed to examine the internal flow field without combustion, with a particular focus on mixing dynamics and flow structures. Multiple mesh configurations are evaluated and benchmarked against a WMLES reference simulation to determine the best compromise between accuracy and computational cost. Subsequently, the engine is ignited using two different strategies, and a detailed post-processing analysis is conducted to investigate detonation behavior and engine performance, with emphasis on DDT processes, non-idealities, and loss mechanisms. Additionally, the response of the injectors is examined, including the flow dynamics within the upstream plenums feeding the annular chamber. All in all, this work contributes to the growing body of knowledge on RDE technology, offering insights into design optimization and performance enhancement for future propulsion systems. It extends current understanding by analyzing the behavior of high-fidelity numerical simulations, while providing valuable perspectives on detonation onset and the mechanisms responsible for performance losses.