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Hypersonic flow over spherically blunted cone capsules for atmospheric entry, Part 2: Vibrational non-equilibrium effects

Martinez Schramm, Jan and Hannemann, Klaus and Hornung, Hans G. (2023) Hypersonic flow over spherically blunted cone capsules for atmospheric entry, Part 2: Vibrational non-equilibrium effects. Journal of Fluid Mechanics, 954 (32), A32-1. Cambridge University Press. doi: 10.1017/jfm.2022.1014. ISSN 0022-1120.

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Official URL: https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/hypersonic-flow-over-spherically-blunted-cone-capsules-for-atmospheric-entry-part-2-vibrational-nonequilibrium-effects/833E299CA463DB13CF54DF4AB012545C


Atmospheric entry capsules shaped as spherically blunted, large apex-angle cones are widely used in space missions. In Part 1 of this study (Hornung et al. (2019)) we explored flows over the two elements of the capsule shape, the sphere and the sharp cone with detached shock, theoretically and computationally. Using a large number of inviscid, perfect-gas computations, analytical functions of two independent variables, the normal-shock density ratio and a cone-angle parameter were found for the dimensionless shock wave stand-off distance and the drag coefficient of a sharp cone. An analytical description was found for the shock stand-off distance in the transition from the 90 degree cone (flat-faced cylinder) to the sphere. In Part 1 it was speculated that the perfect-gas results have relevance to non-equilibrium situations if the normal-shock density ratio is replaced by the density ratio based on the average density along the stagnation streamline. In Part 2 the investigation is extended to blunted-cone capsule shapes. High-precision force measurements and schlieren image analysis are performed in the High-Enthalpy Shock Tunnel Göttingen (HEG) of the German Aerospace Centre using air as test gas, at conditions where vibrational non-equilibrium effects are significant. Accordingly, results are compared to viscous numerical predictions using different physico-chemical models. A theoretical model is constructed for the density profile along the stagnation streamline that is determined by the free-stream conditions and gives the average density. Comparisons of the experimental and numerical results for the dimensionless shock stand-off distance and the drag coefficient, with the extension of the analytical functions of Part 1 to vibrationally relaxing flow exhibit very good agreement in all of a range of geometries.

Item URL in elib:https://elib.dlr.de/192031/
Document Type:Article
Title:Hypersonic flow over spherically blunted cone capsules for atmospheric entry, Part 2: Vibrational non-equilibrium effects
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Martinez Schramm, JanUNSPECIFIEDhttps://orcid.org/0000-0002-8891-6253UNSPECIFIED
Hannemann, KlausUNSPECIFIEDhttps://orcid.org/0000-0002-9653-4087UNSPECIFIED
Hornung, Hans G.California Institute of Technology, Pasadena, CAUNSPECIFIEDUNSPECIFIED
Date:6 January 2023
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:A32-1
Publisher:Cambridge University Press
Keywords:hypersonic flow, blunt cone, vibrational non-equilibrium, free flying model technique, HEG, DLR
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Reusable Space Systems and Propulsion Technology
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Spacecraft, GO
Deposited By: Martinez Schramm, DR Jan
Deposited On:10 Jan 2023 14:09
Last Modified:21 Sep 2023 12:46

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