Investigation of Three RDE Architectures for Propulsion Applications

Abstract

The objective of these investigations is to develop methodologies to enable advanced design and development of a detonation combustor for propulsion applications. Three different Rotating Detonation Engine (RDE) architectures namely Annular-RDE, Disk-RDE and a Flow-through Center-Body Less RDE (CBL-RDE) are investigated in the present ongoing study, to assess and discriminate between these combustor configurations for use with propulsion applications. The present investigation focuses on advanced conceptual design methods and analyses, in which RD-based combustor architectures are investigated using predictions from analytical models namely, a phenomenological model and a time resolved unsteady 3D CFD model. The validated results of the 3D CFD model are used not only to fine tune the assumptions and correlations embedded in the phenomenological model, but also to validate the phenomenological model, establish operability characteristics, and to estimate RDE combustor performance metrics. These metrics will be used to optimize combustor geometric features to ensure they meet the application requirements. Previously, the present authors reported their computational investigations of a 6” Annular-RDE and a 6” Disk-RDE. The computational work reported in this paper focuses on the parametric studies of a Flow-through CBL-RDE architecture and explores the geometry and operational parameter space to map out operability and scalability. Both instantaneous predictions and time-averaged results are discussed. Strong detonations are predicted for 6” Annular-RDE and 6” Disk-RDE (without an exit nozzle) at atmospheric conditions. Only fast flames / thermos-acoustic flames, characterized by unsteady and lower amplitude scalar fluctuations, are predicted for 6” Flow-through CBL-RDE (with or without an exit nozzle) for the geometric and operating parameters considered in this study. In the Flow-through CBL-RDE simulations reported here, four different classes of flames are predicted: (i) highly unstable weak detonations, (ii) steady and strong detonations, (iii) highly unsteady Fast flame / thermoacoustic flames with a single dominant frequency, and (iv) deflagration flames with no frequency component. Using this approach, the relative strengths and weaknesses of each of these architectures to meet the detonation-based propulsion combustor design requirements are summarized.