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Formation of transverse waves in oblique detonations

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Author: Verreault, J. · Higgins, A.J. · Stowe, R.A.
Type:article
Date:2013
Source:Proceedings of the Combustion Institute, 2, 34, 1913-1920
Identifier: 469520
doi: doi:10.1016/j.proci.2012.07.040
Keywords: Ballistics · Adaptive mesh refinement · Detonation structure · Method of characteristics · Oblique detonation wave · Adaptive mesh refinement · Adaptive refinement · Cellular structure · Computational simulation · Detonation structures · Flow field simulation · Method of characteristics · Oblique detonation waves · Shock fronts · Shock induced combustion · Spatial oscillations · Transverse waves · Uniform flow · Activation energy · Facings · Flow fields · Numerical analysis · One dimensional · Shear waves · Shock waves · Waves · Detonation · Defence Research · Defence, Safety and Security · Mechatronics, Mechanics & Materials · WS - Weapon Systems · TS - Technical Sciences

Abstract

The structure of oblique detonation waves stabilized on a hypersonic wedge in mixtures characterized by a large activation energy is investigated via steady method of characteristics (MoC) calculations and unsteady computational flowfield simulations. The steady MoC solutions show that, after the transition from shock-induced combustion to an overdriven oblique detonation, the shock and reaction complex exhibit a spatial oscillation. The degree of overdrive required to suppress this oscillation was found to be nearly equal to the overdrive required to force a one-dimensional piston-driven detonation to be stable, demonstrating the equivalence of two-dimensional steady oblique detonations and one-dimensional unsteady detonations. Full unsteady computational simulations of the flowfield using an adaptive refinement scheme showed that these spatial oscillations are transient in nature, evolving in time into transverse waves on the leading shock front. The formation of left-running transverse waves (facing upstream) precedes the formation of right-running transverse waves (facing downstream). Both sets of waves are convected downstream away from the wedge in the supersonic flow behind the leading oblique front, such that the mechanism of instability must continuously generate new transverse waves from an initially uniform flow. Together, these waves define a cellular structure that is qualitatively similar to a normal propagating detonation. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.