Flow-field analysis and performance assessment of rotating detonation engines under different number of discrete inlet nozzles

TL;DR

This paper investigates how the number of inlet nozzles affects the stability and performance of rotating detonation engines using detailed numerical simulations, revealing that more nozzles lead to more stable and efficient combustion.

Contribution

It provides a systematic numerical analysis of the impact of discrete inlet nozzles on RDE dynamics and performance, highlighting the importance of reactant injection configuration.

Findings

Fewer nozzles cause chaotic detonation fronts and reduced performance.

More nozzles result in stable detonation waves and improved engine metrics.

Numerical simulations accurately capture flow field and detonation behavior.

Abstract

This study explores in depth rotating detonation engines (RDEs) fueled by premixed stoichiometric hydrogen/air mixtures through two-dimensional numerical simulations including a detailed chemical kinetic mechanism. To model the spatial reactant non-uniformities observed in practical RDE combustors, the referred simulations incorporate different numbers of discrete inlet nozzles. The primary focus here is to analyze the influence of reactant non-uniformities on detonation combustion dynamics in RDEs. By systematically varying the number of reactant injection nozzles (from 15 to 240), while maintaining a constant total injection area, the study delves into how this variation influences the behavior of rotating detonation waves (RDWs) and the associated overall flow field structure. The numerical results obtained here reveal significant effects of the number of inlets employed on both RDE stability (self-sustaining detonation wave) and performance. RDE configurations with a lower number of inlets exhibit a detonation front with chaotic behavior (pressure oscillations) due to an increased amount of unburned gas ahead of the detonation wave. This chaotic behavior can lead to the flame extinguishing or decreasing in intensity, ultimately diminishing the engine's overall performance. Conversely, RDE configurations with a higher number of inlets feature smoother detonation propagations without chaotic transients, leading to more stable and reliable performance metrics. This study uses high-fidelity numerical techniques such as adaptive mesh refinement (AMR) and the PeleC compressible reacting flow solver. This comprehensive approach enables a thorough evaluation of critical RDE characteristics including detonation velocity, fuel mass flow rate, impulse, thrust, and reverse pressure waves under varying reactant injection conditions.