Doctorant sous la direction de None

Titre de la thèse: New strategy of spectral estimation for the analysis of vibration of turbomachine blade from tip-timing signals
Résumé de la thèse: In the context of the certification of its helicopter engines, Safran Helicopter Engines performs tests during operation for the measurement of vibratory reponses of various components. The main way to perform measurements is achieved with the tip-timing technologies. This measurement is non-contact and allow to observe the vibration of all the rotor blades when the latter is rotating. Tip-timing consists of a set of sensors set on the stator located around the rotor, which detect the passage time of the blades when they rotate. From these time passages, it is possible to rebuild the vibrational response of each blades. However, by the nature of the acquisition, tip-timing signals have mainly two special features: - A periodic irregular sampling pattern,. - An important sub-sampling of the frequency content to estimate. These special features give rise to difficulties to estimate the frequency content of these signals due to multiple artifacts linked to aliasing physical lines.