Thèse de doctorat
Résumé : The motion of the free liquid surface inside a reservoir is called sloshing. Itis of large interest in different industrial fields such as satellite and spacecrafttrajectory control, automotive industry, nuclear engineering, buildingdesign, etc. The framework of propellant management on spacecraft is ofmain interest for this PhD thesis, even if its outcome can be applied to manyother fields concerned by sloshing.Being able to understand the behavior of the fluid in a reservoir subjectedto extreme environmental conditions means being able to predict its positionand topology inside the tank, for a given external and gravitationalacceleration and a determined thermodynamic condition. The predictionand control of this motion is far from being understood due to the differentparameters that play a role in the dynamic system such as the geometryof the container, the type of external excitation (shape, frequency contentand amplitude), the level of the liquid and finally the kind of liquid. In particular,the design of propulsion systems are affected by this phenomenon,still hampered by the unavailability of validated CFD models. Moreover theexisting experimental studies are mainly based on intrusive and local singlepoint measurement techniques, which give no information on the behaviorof the 3D liquid interface and on the velocity field inside the liquid phase.The main goal of this project has been to extend the experimental approachof liquid sloshing investigation in space propulsion, studying, developing andimproving non-intrusive measurement techniques for free surface behaviorand velocity characterization in the liquid phase. In particular, the free surfacebehavior have been studied by means of Laser Detection and Recordingtechnique (LeDaR), retrieving the profile of the interface over a line, andReference Image Topography technique (RIT), capturing the instantaneous3D interface shape. In addition, Particle Image Velocimetry (PIV) have beenused to measure the 2D velocity field in the main section of the reservoir.Tests performed with water were used as simpler test case to perform thetechniques while liquid nitrogen has been used as replacement uid havingphysical properties similar to real space propellants.The experimental problems of the selected measurement techniques relatedto the particular application have been addressed and a solution has beenproposed. Especially, the selection of tracers which could comply with theuse of a cryogenic fluid while for RIT the possibility to deal with circulardomains and to measure the absolute value of the liquid level. Finally, PIV in wavy ows needed to deal with dynamic curved interfaces for whicha widely-accepted processing algorithm was not available in literature andbesides, the choice of the particles and their seeding procedure in cryogenicsfluids had to be solved.Some applications are shown, which present the potentiality of the techniquesfor a new insight on sloshing flows with the future purpose of providingan accurate database for the verification and validation of numericalsimulations and a better understanding of the phenomena.