Effects of flame jet configurations on detonation initiation

Ishii, Kotaro; Akiyoshi, Takenori; Gonda, Maki; Murayama, Masaru

doi:10.1007/978-3-540-85168-4_37

Cited by 7 publications

(2 citation statements)

References 4 publications

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“…Subsequently, plenty attention had been poured on effect of jet intensity on DDT. Lots of research had been investigated jet intensity by changing the structure of the hot jet tube, and the same conclusion was obtained that the initiation time and distance of DDT were short when the jet intensity is sufficient [22][23][24][25]. Using ethylene/oxygen with nitrogen diluted, He et al [26] explored the effects of different jet velocity on DDT distance.…”

Section: Introductionmentioning

confidence: 90%

Numerical Simulation of Hot Jet Detonation with Different Ignition Positions

et al. 2019

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Ignition position is an important factor affecting flame propagation and deflagration-to-detonation transition (DDT). In this study, 2D reactive Navier–Stokes numerical studies have been performed to investigate the effects of ignition position on hot jet detonation initiation. Through the stages of hot jet formation, vortex-flame interaction and detonation wave formation, the mechanism of the hot jet detonation initiation is analyzed in detail. The results indicate that the vortexes formed by hot jet entrain flame to increase the flame area rapidly, thus accelerating energy release and the formation of the detonation wave. With changing the ignition position from top to wall inside the hot jet tube, the faster velocity of hot jet will promote the vortex to entrain jet flame earlier, and the DDT time and distance will decrease. In addition, the effect of different wall ignition positions (from 0 mm to 150 mm away from top of hot jet tube) on DDT is also studied. When the ignition source is 30 mm away from the top of hot jet tube, the distance to initiate detonation wave is the shortest due to the highest jet intensity, the DDT time and distance are about 41.45% and 30.77% less than the top ignition.

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Section: Introductionmentioning

confidence: 90%

Numerical Simulation of Hot Jet Detonation with Different Ignition Positions

et al. 2019

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“…The mainstream initiation methods include optical ignition, 3 shock wave focusing ignition, 4 nanosecond plasma ignition, 5 multipoint successive ignition, 6 and jet ignition 7 , etc. Ishii et al 8 obtained the detonation initiation and propagation process of hot jet in incoming flow with Mach numbers 0.9 and 1.2 through experimental study. Han et al 9 researched the detonation initiation and deflagration to detonation transition (DDT) process of hot jet in supersonic premixed gas by experiment and numerical simulation, and found that the hot jet detonation was essentially initiated by the reflected shock wave formed by the induced bow shock wave at the upper wall.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on detonation initiation process in the chamber with characteristic structures of the dual-mode scramjet combustor

Wei

Wang

Qin

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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In order to improve the performance of traditional ramjet, a ramjet based on pulse detonation (PD-Ramjet) instead of isobaric combustion was proposed. Several special-shaped detonation chambers which retained the characteristic structures of the dual-mode scramjet combustor were designed. Characteristic structures included the expansion channel and the cavity. The filling process and detonation initiation process of the stoichiometric hydrogen/air mixture under the incoming flow condition of the sub-combustion mode were studied in the detonation chambers with characteristic structures by two-dimensional numerical simulation method, and the influences of the characteristic structures on the filling process and detonation initiation process were analyzed. The simulation and analysis results indicated that the hydrogen concentration at both sides of the chamber near the outlet was low due to the structure of the expansion channel, and the pressure and velocity of the detonation wave decreased gradually after the expansion channel. The cavity had a significant influence on the filling process, which resulted in the uneven hydrogen concentration downstream the cavity, especially near the outlet of the chamber. The intensity of the detonation wave attenuated to a certain extent by reason of the cavity, where the peak pressure first decayed due to the sudden expansion of the flow path and then rose owing to the reflection at the cavity aft wall.

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Phenomenon and analysis of direct initiation of detonation using multiple turbulent flame jets

Lei

Zhao

et al. 2022

Physics of Fluids

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This work reports the experimental investigations on direct initiation of detonation using multiple turbulent flame jets, with a special focus on the jet arrangement schemes and fundamental physics in the initiation processes. Results show that the direct initiation of detonation can be achieved by using turbulent jets even under the conditions that the tube diameter is much smaller than the empirical critical tube diameter with a mechanism of flame-shock-wall interaction. Conspicuous evidence has been shown that the probability of direct detonation initiation improves significantly near the detonatability limit using multi-jets compared to single jets. These results are found to be linked to several new phenomena observed when using the multiple jets to initiate the chamber. They are: 1) the unexpected rapid promotion of final-stage flame acceleration in ignition tubes by multiple jets, which is attributed to the fact that the expanding precursor shock waves propagate back into the adjacent tube and encounter the flame; 2) the enhancement of hot spot generation by multiple jets due to the precursor shock intersecting and the formation of an induction zone; 3) the obvious velocity loss in impinging jets initiation as a result of induced hot spots propagating in the burned gases.

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Effects of flame jet configurations on detonation initiation

Cited by 7 publications

References 4 publications

Numerical Simulation of Hot Jet Detonation with Different Ignition Positions

Numerical Simulation of Hot Jet Detonation with Different Ignition Positions

Numerical study on detonation initiation process in the chamber with characteristic structures of the dual-mode scramjet combustor

Phenomenon and analysis of direct initiation of detonation using multiple turbulent flame jets

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