Testing of a Small Turbocharger/Turbojet Sized Simulator Rotor Supported on Foil Bearings

A small rotor designed to simulate a miniature turbojet engine or turbocharger rotor mounted on compliant foil bearings was tested at speeds in excess of $150,000rpm$ and temperatures above $260°C$$(500°F)$⁠. The simulator rotor-bearing system was operated while positioned in various orientations and was subjected to transient shock impacts exceeding $35g$⁠. Subsequent testing was completed to demonstrate the capabilities of miniature thrust foil bearings as well. The tested rotor weighed approximately $400g$ and used $15mm$ diameter foil journal bearings and a multipad $25mm$ diameter double acting thrust foil bearing. Results of the rotor-bearing system dynamics are presented along with experimentally measured natural frequencies, rotor displacements, and thrust load carrying ability. A good correlation between measurement and analysis is observed. Very short rotor acceleration times from rest to maximum speed were also measured. A parallel test simulator has been used to accumulate over 1000 start-stop cycles to demonstrate the life of the bearing and coating. Based on this successful testing, it is expected that the goal of developing oil-free turbochargers and small turbojet engines that operate at high speeds with long life will be achieved.