Numerical Study of Detonation Stabilization by Finite Length Wedges

Walter, Miguel; Silva, Luı́s Fernando Figueira da

doi:10.2514/1.12417

Cited by 18 publications

(5 citation statements)

References 26 publications

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“…Thus, the ODW is reduced to the CJ ODW downstream of the beginning of the interaction. This result is similar to those obtained by Papalexandris [29] and Walter and Silva [30], which indicates that the numerical results in this paper are reasonable. To verify the criterion further, we analyze more cases with different Mach numbers and 40 kPa inflow pressure.…”

Section: Verification Of the Initiation Criterionsupporting

confidence: 92%

“…The expansion wave derived from the wedge turning point may quench the ODW [28,29]. Walter and Silva [30] found that a CJ ODW was obtained for intermediate wedge angles, and the decoupling of the ODW was observed for wedge angles near the maximum attach angle. Fang et al [31] investigated the effects of expansion waves on the two initiation mechanisms of ODWs and found that the structure of the wave-controlled initiation was more sensitive to the expansion waves than the kinetic-controlled initiation.…”

Section: Introductionmentioning

confidence: 98%

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Criticality for Oblique Detonation Waves Induced by a Finite Wedge in a Hydrogen–Air Mixture

Qin

Zhu

2023

Aerospace

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Two-dimensional oblique detonation waves (ODWs) induced by finite wedges in a stoichiometric hydrogen–air mixture have been investigated numerically based on reactive Euler equations with a detailed chemical reaction model. The main zone affected by the expansion wave emanating from the turning point of a wedge is the flowfield downstream of the intersection point of the oblique shock wave (OSW) and the expansion wave. The ODW would be reduced to Chapman–Jouguet (CJ) detonation or decoupled combustion downstream. Three combustion regimes, detonation, decoupled combustion, and no ignition, were observed successively, as the wedge length decreases. It is found that the location of the intersection point is a key parameter for the detonation initiation. When the intersection point is located upstream of the ODW transition point, the expansion wave may quench ODW. Then, the critical wedge length is obtained by theoretical analysis of wave structures and the initiation criterion of ODWs for finite wedges is proposed. When the wedge length is greater than the critical wedge length, ODWs can be initiated. On the contrary, the initiation of ODWs do not occur. For wedge lengths small enough, no ignition occurs. Previously proposed criteria that use the induction length are also examined and compared with the present critical wedge length criterion in this study, and the latter is proven to achieve better results.

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Section: Verification Of the Initiation Criterionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 98%

Criticality for Oblique Detonation Waves Induced by a Finite Wedge in a Hydrogen–Air Mixture

Qin

Zhu

2023

Aerospace

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“…Fedkiw et al, 1 Oran et al, 2 Hu et al, 3 Wang et al, 4 Walter and da Silva, 5 He and Karagozian, 6 Aslam and Powers, 7 or Tsuboi et al 8 However, there are indications that such an assumption can be problematic. For example, using grid sizes around 10 −6 m for their threedimensional simulations of unsteady H 2 -air detonations, Tsuboi et al report wave dynamics that show strong sensitivity to the fineness of the grid.…”

Section: Introductionmentioning

confidence: 99%

The Dynamics of Unsteady Detonation with Diffusion

Aslam

Romick

Powers

2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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The dynamics of one-dimensional detonations predicted by a one-step irreversible Arrhenius kinetic model with the inclusion of mass, momentum, and energy diffusion were investigated. A series of calculations in which activation energy is varied, holding the length scales of diffusion and reaction constant, was performed. As in the inviscid case, as the activation energy increases, the system goes through a period-doubling process and eventually undergoes a transition to chaos. Within the chaotic regime, there exist regions of low frequency limit cycles. An approximation to Feigenbaum's constant, the rate at which bifurcation points converge, is obtained. The addition of diffusion significantly delays the onset of instability and strongly influences the dynamics in the unstable regime. Because the selected reaction and viscous length scales are representative of real physical systems, the common use of reactive Euler equations to predict detonation dynamics in the unstable and marginally stable regimes is called into question; reactive Navier-Stokes may be a more appropriate model in such regimes.

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“…Fusina et al [18] studied numerically the stability of a wedge supported ODW near the Chapman-Jouguet (C-J) point in an inhomogeneous fuel-air mixture that introduced artificially small disturbances consisting of pure air. A numerical study conducted by Walter et al [19] was on the interaction between the leading C-J ODW stabilized on a finite length wedge and expansion waves that generated from a wedge shoulder.…”

Section: Introductionmentioning

confidence: 99%

Visualization of the non-steady state oblique detonation wave phenomena around hypersonic spherical projectile

Maeda¹,

Inada²,

Kasahara³

et al. 2011

Proceedings of the Combustion Institute

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Colloquium that describes the research topic:DETONATIONS, EXPLOSIONS AND SUPERSONIC COMBUSITON including pulse-detonation and scramjet engines. Total length of paper and method of determination:5811 words (method 1) 6. List word equivalent lengths for main text, nomenclature, references, each figure with caption, and each AbstractWe studied experimentally the shock waves and combustion waves generated by a hypersonic spherical projectile in an explosive mixture. An acetylene / oxygen mixture diluted with argon (2C 2 H 2 + 5O 2 + 7Ar) was used with various initial pressures (detonation cell sizes) to observe optically with a shadowgraph imaging system a shock-induced combustion (SIC), a stable oblique detonation wave (ODW), and a wave called a Straw Hat type consisting of a strong SIC and ODW. The criticality of stabilizing an ODW around a projectile is expressed by the ratio of the projectile diameter, d, to the cell size, λ, as d / λ = 3.63～4.84. Although the Straw Hat type wave in the vicinity of criticality is an unstable phenomena, it has been mainly observed by a single frame picture to date, so that it is difficult to discuss the time history of its wave structure. In this study, it was remarkable to directly carry out continuous optical observations using a high speed video camera which can continuously film 100 pictures with a 1 μs frame speed so as to allow an investigation of the sustaining mechanism of the unstable wave structure.Our results allowed the identification of an increase in unsteadiness in the relative distance between the projectile fronts and the transition points to an ODW as the time increased. They also showed local explosions in the SIC region near transition point transformed the ODW front upstream.(239 words)

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Numerical Study of Detonation Stabilization by Finite Length Wedges

Cited by 18 publications

References 26 publications

Criticality for Oblique Detonation Waves Induced by a Finite Wedge in a Hydrogen–Air Mixture

Criticality for Oblique Detonation Waves Induced by a Finite Wedge in a Hydrogen–Air Mixture

The Dynamics of Unsteady Detonation with Diffusion

Visualization of the non-steady state oblique detonation wave phenomena around hypersonic spherical projectile

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