Kévin Lauzier soutient sa thèse le 18/09/2020 à 10:00.
Lieu : amphi Émilie du Châtelet (bibliothèque INSA).
Jury :
Rapporteurs : GODOY Emmanuel, HUBERT Arnaud
Examinateurs : GERBAUD Laurent, DUVAL Jean-Marc
Directrice de thèse : LIN SHI Xuefang (Ampère)
Co-encadrants de thèse: BRIBIESCA ARGOMEDO Federico, GAUTHIER Jean-Yves, SESMAT Sylvie (Ampère)
Invités: CARVALHO LOPES Diogo, GARDELEIN Arnaud
Abstract :
Earth observation satellites for meteorological, scientific or military applications sometimes carry infrared imagers. These cameras need to be cooled down to very low temperatures in order to avoid blurry infrared pictures of the Earth, due to the thermal noise of the detector or heat sources nearby. This PhD thesis focuses on a pulse tube cryocooler used in such applications. It deals with induced vibrations as they can destabilize the satellite or make the camera focal plane move. The goals are to understand and reduce the vibrations induced by the pulse tube cryocooler. These PhD works are composed of two main parts. First, the cryocooler is analyzed and modelled to reproduce observed induced vibrations. This global multiphysics model is aimed at identifying dissymmetry, non-linearity and mechanical behaviors which cause vibrations. This approach uses different fields of science such as electromagnetism, mechanics, fluid mechanics and thermodynamics. Sensitivity studies are done and the model is confronted to experiments highlighting measurement tools limits and checking methodologies. Next, vibration reduction using control strategies is studied. The whole control loop is questioned. The improvements proposed concern the vibration sensors, the frequency analysis algorithm, the vibration reduction algorithm and the type of control. Solutions for control, conception and manufacturing resulting from this PhD work offer opportunities to improve the system and lower its cost.
Key Words : non-linear multiphysics modeling, active vibration control, linear electromagnetic actuator, fluid dynamics of oscillatory flow, cryocooler, pulse tube, oxford type compressor, vibration measurement, frequency analysis