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Effect of Source Geometry on Fully Expanding Free Jets

Grabe, Martin and Dettleff, Georg and Hepp, Christian and Hannemann, Klaus (2018) Effect of Source Geometry on Fully Expanding Free Jets. In: AIP Conference Proceedings, 2132 (030001). American Institute of Physics Inc.. 31st International Symposium on Rarefied Gas Dynamics 2018, 23.-27. Jul. 2018, Glasgow, Scotland. DOI: 10.1063/1.5119526 ISBN 978-073541874-5 ISSN 0094243X

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Official URL: http://www.jwfl.ac.uk/event_detail.cfm?pid=07C7020B-AC36-4F5B-BA23-1BE3EC1C67D9


Underexpanded free jets issuing from sonic orifices are a fundamental flow in rarefied gas dynamics and as such have been studied extensively both in theory and experiment. An analysis of jet plumes originating from rather high pressure reservoirs and expanding freely into high vacuum pose difficulties to both approaches. Especially most test facilities cannot provide and sustain a background pressure low enough to permit expansion of the jet into the free molecule flow regime. The High-Vacuum Plume Test Facility for Chemical Thrusters (STG-CT) at the DLR site in Göttingen is designed for the particular purpose of studying free plume expansion, employing a liquid-helium driven cryo pump. In this work we compare mass flux angular profiles of two different sonic flow sources, recorded with a free molecule impact pressure probe ("Patterson probe"). Both sources have a reservoir-to-exit diameter ratio of D/d∗=27 at a common exit diameter d∗ = 0.6 mm, but one is a flat-faced cylinder into whose face a square edged orifice is centrally machined, the other source features a sharp-edged orifice whose outer walls are inclined backwards 135 degrees from the axis. Nitrogen gas is used throughout this study. The free expansion is found to be hindered at angles well smaller than 90 degrees, and comparison with the conical flow source indicates that the disturbance likely arises from interaction of plume gas with the outer surface of the flat-faced source. This effect has to our knowledge previously not been been described before and will be studied here in more detail.

Item URL in elib:https://elib.dlr.de/119790/
Document Type:Conference or Workshop Item (Poster)
Title:Effect of Source Geometry on Fully Expanding Free Jets
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Grabe, Martinmartin.grabe (at) dlr.deUNSPECIFIED
Dettleff, Georggeorg.dettleff (at) dlr.deUNSPECIFIED
Hepp, ChristianChristian.Hepp (at) dlr.deUNSPECIFIED
Hannemann, Klausklaus.hannemann (at) dlr.deUNSPECIFIED
Date:5 August 2018
Journal or Publication Title:AIP Conference Proceedings
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1063/1.5119526
Publisher:American Institute of Physics Inc.
Keywords:Plume, Orifice, STG-CT
Event Title:31st International Symposium on Rarefied Gas Dynamics 2018
Event Location:Glasgow, Scotland
Event Type:international Conference
Event Dates:23.-27. Jul. 2018
Organizer:University of Strathclyde
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 - Wiederverwendbare Raumfahrtsysteme und Antriebstechnologie
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Spacecraft, GO
Deposited By: Grabe, Martin
Deposited On:26 Nov 2018 17:09
Last Modified:13 Nov 2019 16:35

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