Test Facility Chill Down Procedure Optimization and Load Assessment Troubleshooting in a Test Rig for Hybrid Bearing Characterization

Since the beginning of space exploration, launch operations have represented one of the main cost drivers. Even though propulsion technologies have evolved and several propulsion systems are now available, the high thrust requirement still makes chemical rockets the only feasible solution for launch operations, despite their costs due to their expendable nature. As a result, rocket reusability has been identified as a key strategy to reduce both launch cost and time. However, several challenges arise when addressing rocket reusability, such as the ones related to the turbopump operations, usually required for liquid propellant pressurization. Due to their performance and characteristic, ball bearings have traditionally represented the most reliable choice to support the turbopump during its operations. However, the deformations of the rolling elements associated to the extreme loads that are generated during launch makes the overall system non-reusable. Journal bearings offer a promising alternative, potentially allowing the system to operate with no contact between the rotating and the stationary elements. In this context, University of Pisa along with the European Space Agency (ESA) have designed and developed a journal bearing protype along with a dedicated cryogenic test facility. Liquefied Natural Gas (LNG) was selected as the working fluid, being one of the most adopted green propellant adopted in next-generation launchers. The project, named “Journal Bearing Assessment for Reusable Turbopump (B.A.R.T.) project”, aims at testing and characterizing the performance of these devices to address their suitability for reusable launcher systems. The following thesis describes the project activities carried out, focusing on the characterization of the system’s functionality and performance in preparation for the upcoming experimental test of the journal bearing prototype.