Oblique Detonations: Theory and Propulsion Applications

Powers, Joseph M.

doi:10.1007/978-94-011-1050-1_12

Cited by 19 publications

(11 citation statements)

References 55 publications

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“…Its basic research has significant value to the generic knowledge of high-speed compressible reacting flows. 1 In recent years, oblique detonation as an alternative for supersonic combustion has gained significant interest for air-breathing, hypersonic propulsion systems because of its potential to offer greater efficiency. [2][3][4] This combustion mode has led to the development of Oblique Detonation Wave (ODW) engines and ram accelerators.…”

Section: Introductionmentioning

confidence: 99%

Initiation structure of oblique detonation waves behind conical shocks

Yang

Teng

et al. 2017

Physics of Fluids

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The understanding of oblique detonation dynamics has both inherent basic research value for highspeed compressible reacting flow and propulsion application in hypersonic aerospace systems. In this study, the oblique detonation structures formed by semi-infinite cones are investigated numerically by solving the unsteady, two-dimensional axisymmetric Euler equations with a one-step irreversible Arrhenius reaction model. The present simulation results show that a novel wave structure, featured by two distinct points where there is close-coupling between the shock and combustion front, is depicted when either the cone angle or incident Mach number is reduced. This structure is analyzed by examining the variation of the reaction length scale and comparing the flow field with that of planar, wedge-induced oblique detonations. Further simulations are performed to study the effects of chemical length scale and activation energy, which are both found to influence the formation of this novel structure. The initiation mechanism behind the conical shock is discussed to investigate the interplay between the effect of the Taylor-Maccoll flow, front curvature, and energy releases from the chemical reaction in conical oblique detonations. The observed flow fields are interpreted by means of the energetic limit as in the critical regime for initiation of detonation.

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Section: Introductionmentioning

confidence: 99%

Initiation structure of oblique detonation waves behind conical shocks

Yang

Teng

et al. 2017

Physics of Fluids

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“…On the other hand, applications using stabilized shock-induced combustion (SIC) and self-sustained oblique detonation waves (ODW) (Lehr [9], Li et al [10]) around projectiles are proposed for oblique detonation wave engines (ODWEs) (Powers [11]) and a Ram-Accelerator (RAMAC) (Hertzberg et al [12], Higgins [13]). The fundamental researches on these phenomena include both experimental and numerical ones.…”

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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“…The computed forces on the projectile would enter into the acceleration of the reference frame, which would then alter the inflow Mach number dynamically. Also as suggested in an upcoming review by Powers 30 , it would be useful to study this problem in the context of other welldocumented inert flows such as a Busemann biplane or flow over a thin airfoil.…”

Section: Discussionmentioning

confidence: 99%

Calculations for steady propagation of a generic ram accelerator configuration using the Roe method

Grismer

Powers

1994

32nd Aerospace Sciences Meeting and Exhibit

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This study describes a methodology and gives analysis to determine the steady propagation speed of a projectile fired into a gaseous mixture of fuel and oxidizer. For tractability, the steady supersonic flow of an inviscid calorically perfect ideal reacting gas with high activation energy over a symmetric double wedge, unconfined by a cowl, is considered. Propagation speeds are found which give rise to shocks of such strength as to induce a reaction zone to be in a region which allows the combustion-induced thrust to balance the wave drag. For a fixed heat release greater than a critical value, two steady propagation speeds are predicted. The solution at the higher Mach number is stable to quasi-static perturbations while the solution at the lower Mach number is unstable. This methodology can be applied to analyze devices which have more complex geometries, such as the ram accelerator or oblique detonation wave engine.

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Oblique Detonations: Theory and Propulsion Applications

Cited by 19 publications

References 55 publications

Initiation structure of oblique detonation waves behind conical shocks

Initiation structure of oblique detonation waves behind conical shocks

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

Calculations for steady propagation of a generic ram accelerator configuration using the Roe method

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