Modellazione degli effetti dell’iniezione e dell’accoppiamento con il plenum sulla dinamica del motore a detonazione rotante

Abstract

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Pressure-gain combustion technologies represent a promising solution for increasing combustion efficiency, offering thermodynamic advantages over conventional deflagrative systems through an approximate isochoric combustion process. Rotating Detonation Engines (RDEs) are able to sustain a continuously propagating detonation wave within an annular chamber, obtaining a net total pressure increase at the outlet. These characteristics make RDEs a compelling subject of investigation, motivating the present work. The predominant flow and combustion characteristics of hydrogen-air RDEs are explored through CFD simulations carried out with the open-source software OpenFOAM. Two configurations are investigated: a two-dimensional unwrapped premixed simulation with discrete injection and plenum coupling, solved under varying inlet total pressure conditions, and a fully three-dimensional non-premixed simulation of a complete annular engine, preceded by a preliminary cold-flow analysis to characterize the internal flow field prior to combustion. In both configurations, the stable detonation regime is reached after several detonation cycles. The interaction between the plenum and the backpressure induced by the static pressure field behind the detonation front is identified as a determining factor in setting the chamber operating conditions. This influence both the local equivalence ratio and the uniformity of the detonation front strength. Higher inlet total pressures are observed to reduce the influence of instabilities. Additionally, in the non-premixed configuration, backpressure-driven re-injection of oxidizer into the hydrogen plenum is observed. The results contribute to the understanding of the coupling mechanisms between injection dynamics and detonation stability, providing a foundation for future design improvements.