Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Fluid motion analysis in the cryogenic tanks of the upperstage of Ariane 5 during the ascent phase
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics.
2017 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In the frame of the improvement of the performances for Ariane 5, an analysis iscarried out to explain the pressure drop observed in the ascent phase of some flights inthe liquid hydrogen (LH2) tank of the upper stage. This stage is mainly idle until therocket is out of the atmosphere but is submitted to important excitation throughoutthe ascent phase in the atmosphere. Due to excitation, the liquid contained in thetank moves and breaks the thermodynamic equilibrium. This movement, sloshing isidentified as the most likely cause of the pressure drop observed. It is investigated inthis thesis to understand how exactly it impacts the thermodynamic equilibrium inthe tank.The pressure drop called creux PGRH can be explained by the mixing of the topof the liquid with the liquid bulk, colder than the top, when the liquid is sloshing.This movement changes the saturation conditions and yields pressure and temperatureevolutions in the ullage volume of the tank. Observations on Ariane 5 flightsshowed that the first asymmetric mode was mainly excited during this first phase ofascension. Simple models such as the pendulum model are used to simulate the dynamicbehaviour of this mode. Its stability is also investigated through lateral andlongitudinal excitations.The thermodynamics of the system in the tank can be modelled by a one-dimensionalmodel. Based on an experiment with liquid nitrogen in a cylindrical tank, the heatfluxes are calculated and plugged in the model. The pressurisation phase is first simulatedthrough self and active pressurisation to estimate the importance of the thicknessof the thermal boundary layer. Sloshing is included in the model thermodynamicallyby considering a more important conductive coefficient in the sloshing layer. The amplitudeof sloshing can be linked to the new conduction term thanks to a literaturerelation but it underestimates the actual magnitude of the pressure drop. The modelis extended to a two-dimensional model to take into account the sloshing mechanically,knowing the velocities from the pendulum model. It is found to be not accurate mostlydue to the turbulence of the sloshing layer not considered in the model.The models give in any case important results regarding the influence of some tankparameters such as the ullage volume, the importance of the pressurisation phase anda necessary distinction between chaotic and stable sloshing. From this, the data ofAriane 5 flights is analysed. The flights are divided in three families according to themagnitude of the pressure drop measured. A fault tree analysis is performed to ruleout possible influences and put forward a theory on the creux eventually.

Place, publisher, year, edition, pages
2017. , p. 82
Series
TRITA-AVE, ISSN 1651-7660 ; 2017:05
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-209187OAI: oai:DiVA.org:kth-209187DiVA, id: diva2:1110758
External cooperation
Airbus Safran Launchers
Examiners
Available from: 2017-06-16 Created: 2017-06-16 Last updated: 2017-06-16Bibliographically approved

Open Access in DiVA

fulltext(2838 kB)87 downloads
File information
File name FULLTEXT01.pdfFile size 2838 kBChecksum SHA-512
54f5a83beccf16a06f97bc6d88b4d2f049b6aef19e578d71a6512548a706866e1b0d49bc398ef33f6f8c9daa756e626c600bad57c60271844a80bb517f2b8e6f
Type fulltextMimetype application/pdf

By organisation
Aerodynamics
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 87 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 149 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf