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Dynamical separation of spherical bodies in supersonic flow

Laurence, Stuart and Parziale, N. J. and Deiterding, Ralf (2012) Dynamical separation of spherical bodies in supersonic flow. Journal of Fluid Mechanics, 713 (12), pp. 159-182. Cambidge University Press. DOI: 10.1017/jfm.2012.453 ISSN 0022-1120

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Official URL: http://dx.doi.org/10.1017/jfm.2012.453

Abstract

An experimental and computational investigation of the unsteady separation behaviour of two spheres in a highly supersonic flow is carried out. The spherical bodies, initially touching, are released with negligible relative velocity, an arrangement representing the idealized binary fragmentation of a meteoritic body in the atmosphere. In experiments performed in a Mach-4 Ludwieg tube, nylon spheres are initially suspended in the test section by weak threads and, following detachment of the threads by the arrival of the flow, fly freely according to the aerodynamic forces experienced. The resulting sphere motions and unsteady flow structures are recorded using high-speed shadowgraphy. The qualitative separation behaviour and the final lateral velocity of the smaller sphere are found to vary strongly with both the radius ratio and the initial alignment angle of the two spheres. More disparate radii and initial configurations in which the smaller sphere centre lies downstream of that of the larger sphere both increase the tendency for the smaller sphere to be entrained within the flow region bounded by the bow-shock of the larger body, rather than expelled from this region. At a critical angle for a given radius ratio (or a critical radius ratio for a given angle), transition from entrainment to expulsion occurs; at this critical value, the final lateral velocity is close to maximum due to the �surfing� effect noted by Laurence & Deiterding (J. Fluid Mech., vol. 676, 2011, pp. 396-431) at hypersonic Mach numbers. A high-precision tracking algorithm is used to provide quantitative comparisons between experiments and high-resolution inviscid numerical simulations, with generally favourable agreement.

Item URL in elib:https://elib.dlr.de/78383/
Document Type:Article
Additional Information:Online published: 26. October 2012, December 2012
Title:Dynamical separation of spherical bodies in supersonic flow
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Laurence, Stuartstuart.laurence (at) dlr.deUNSPECIFIED
Parziale, N. J.California Institute of TechnologyUNSPECIFIED
Deiterding, Ralfralf.deiterding (at) dlr.deUNSPECIFIED
Date:2012
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:713
DOI :10.1017/jfm.2012.453
Page Range:pp. 159-182
Publisher:Cambidge University Press
ISSN:0022-1120
Status:Published
Keywords:Supersonic flows, aerodynamic interactions, meteoroid fragmentation, high-speed flow visualization
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transport
DLR - Research area:Raumfahrt
DLR - Program:R RP - Raumtransport
DLR - Research theme (Project):R - Raumfahrzeugsysteme - Anlagen u. Messtechnik
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Spacecraft
Deposited By: Laurence, Stuart
Deposited On:14 Dec 2012 14:53
Last Modified:31 Jul 2019 19:38

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