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Item type:Publication, Flow-field analysis and performance assessment of rotating detonation engines under different number of discrete inlet nozzles(Elsevier Ltd, 2024-12-01)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. The insights derived from the numerical simulations carried out here enhance the understanding of the fundamental processes governing the performance of RDE concepts. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Extinction of hydrogen enriched methane and propane flames through perforated plates flame arrester elements with varying thickness(Elsevier BV, 2026-05-27)This study investigated the extinction of premixed flames involving methane, propane, hydrogen and air by using a flame arrester element composed of multiple perforated plates. Six stoichiometric mixtures were considered in the experiments, namely, [100%CH4]/air, [25%C3H8+75%H2]/5%He/air, [100%CH4]/10%He/air, [40%C3H8+60%H2]/10%He/air, [75%CH4+25%H2]/air and [10%C3H8+90%H2]/air. Helium was added to three of the mixtures to increase the thermal conductivity and produce different Lewis (Le = 0.72 to 1.36) and Zeldovich numbers (Ze = 4.98 to 8.45). Experiments were performed in a closed duct at 40 kPa and 295 K using flame arrester elements with varying thickness (δplates = 18 to 150 mm) and with orifice diameters of 1.0 and 2.0 mm. The mixtures and arrester configurations were tested at least three times, totaling 240 experiments. A one-dimensional heat-transfer model was also employed to strengthen the interpretation of the experimental observations. The results indicated that mixtures with similar Le and high Ze were successfully extinguished once a sufficiently thick perforated plates assembly was used.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Distorted tulip flame: On the mechanisms controlling premixed flame acceleration in closed channels(Elsevier BV, 2025-12-01)This study numerically investigates premixed flame propagation dynamics accounting for two different wall boundary conditions: (i) free-slip and (ii) non-slip boundary conditions. Direct numerical simulations (DNS) conducted here involved the solution of the fully compressible Navier–Stokes equations coupled with a 21-step chemical kinetic mechanism and full transport properties to quantify the influence of pressure waves on flame propagation. The analysis focuses on primary mechanisms driving flame propagation in confined. Accordingly, the effects of pressure waves on flame dynamics are analyzed, with particular attention to flame shape evolution. In particular, the Rayleigh-Taylor (RT) instability, closely linked to the thermoacoustic instability, and its effect on the flame corrugation are analyzed through the baroclinic torque. The results highlight hat under non-slip conditions, a distorted tulip flame (DTF) forms after the initial tulip flame, strongly influenced by reflected pressure waves and pressure gradients in the reacting flow. Additionally, using Spectral Proper Orthogonal Decomposition (SPOD), a strong coupling between reflected pressure waves, vortex formations, and shape evolution is observed. Particularly, harmonic structures are identified in the pressure wave reflected by the channel end wall that leads to higher harmonics around the flame front due to the non-linear interaction between pressure waves and flame front.5