Testing and Commissioning of a Test Facility for Cryogenic Hybrid Journal Bearings

Nowadays, reusable rockets represent one of the most promising design solutions for reducing launch costs. The achievement of high thrust levels in these rockets is typically dependent on the utilisation of either solid or liquid propellant engines. Liquid propellant rockets are the optimal compromise for this challenge, as they have higher specific impulses than solid propellants and the thrust can be modulated. One of the criticalities of these elements is related, for example, to the use of turbopumps that have a finite lifetime and require maintenance after each launch and substitution of critical elements, such as rolling bearings. To develop the reusability of these devices, it is necessary to develop turbopumps with an extended operational lifetime. Journal bearings offer a promising alternative to traditional rolling bearings, utilising a lubricant film that separates the rotor and stator, thereby reducing wear and extending the operational life of the turbopump. To achieve this objective, the University of Pisa has developed a cryogenic test facility, as part of a project funded by the European Space Agency (ESA), designed to characterise high-speed journal bearings using liquid methane. The objective of this project, called 'Journal Bearings Assessment for Reusable Turbopumps' or BART, is to assess the performance of cryogenic, methane-based journal bearings under typical turbopump operating conditions, including both steady-state and transient loads. The test facility has been designed to assess the performance of three prototypes of journal bearings developed by the research team. The objective of this thesis is to address the testing and commissioning of various components that contribute to the overall functionality of the test facility.