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Measurement of Aerodynamic Coefficients of Blunt Cones at the High Enthalpy Shock Tunnel Göttingen

Friedl, Damian and Martinez Schramm, Jan and Hannemann, Klaus (2016) Measurement of Aerodynamic Coefficients of Blunt Cones at the High Enthalpy Shock Tunnel Göttingen. 11th International Workshop on Shock Tube Technology, 30.06.2016, Göttingen, Deutschland.

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Abstract

During atmospheric re-entry, intense heating of the shock layer leads to vibrational excitation, dissociation and even ionization of the gas near the forefront of the spacecraft, while further downstream, recombination reactions occur. These so called “high-temperature effects” may have a substantial impact on the forces and heat loads imposed on the vehicle. A well-known example is the “pitch-up anomaly” observed during the first Space Shuttle orbiter re-entry: An unforeseen increase of the pitching moment, which was later attributed mainly to high-temperature effects, necessitated the body flap to deflect twice the predicted amount to maintain a trimmed flight. The latest campaign at the High Enthalpy Shock Tunnel Göttingen (HEG) is presented. Its goal is to perform accurate measurements of lift, drag and pitching moment on blunt cones and determine the impact of high-temperature effects on these parameters. During previous experiments at JAXA’s HIEST shock tunnel, differences in the axial force coefficient between measurement and numerical prediction as well as indications of a possible pitch-up effect were found for high enthalpy flows around these geometries. This study aims to investigate whether these observations are facility-dependent or can be reproduced and attributed to high-temperature effects. The second objective is to assess and further improve the accuracy of the employed short-duration force measurement techniques. For the current study, two comparatively light-weight, spherically blunted cone models with varied nose radii were manufactured and positioned in the test section via a detachable support that left them unrestrained after nozzle flow startup (free-flight technique). Experiments were conducted at different angles of attack for low and high enthalpy flow conditions. Forces and moments were measured using two different approaches simultaneously: The first technique derives lift, drag and pitching moment from a high-speed video record of the model movement using an optical tracking algorithm, while the second uses readings of accelerometers mounted inside the model. These approaches are described in detail and first results of both measurement techniques are contrasted with one another and with numerical CFD calculations obtained using the DLR TAU Code. Finally, an outlook is given on how these results relate to the HIEST experiments.

Item URL in elib:https://elib.dlr.de/105275/
Document Type:Conference or Workshop Item (Speech)
Additional Information:WEB-Link: Link folgt wenn verfügbar
Title:Measurement of Aerodynamic Coefficients of Blunt Cones at the High Enthalpy Shock Tunnel Göttingen
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Friedl, Damiandamian.friedl (at) dlr.deUNSPECIFIED
Martinez Schramm, Janjan.martinez (at) dlr.deUNSPECIFIED
Hannemann, Klausklaus.hannemann (at) dlr.deUNSPECIFIED
Date:2016
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:HEG, short-duration force measurement, lift, drag, pitching moment, force coefficient, optical tracking, accelerometer, spherically blunted cone, spherecone, bluntcone, atmospheric re-entry, high-temperature effect, pitch-up anomaly, high enthalpy flow
Event Title:11th International Workshop on Shock Tube Technology
Event Location:Göttingen, Deutschland
Event Type:Workshop
Event Dates:30.06.2016
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: Bachmann, Barbara
Deposited On:26 Sep 2016 15:34
Last Modified:26 Sep 2016 15:34

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