Rotordynamic Instability Control For Floating-Ring Bearing Supported Turbo-Shaft By Angled Oil-Injection Feedholes

Daniel Tamunodukobipi, Yong Bok Lee

Rotordynamic instability is a performance defect common with floating-ring bearing (FRB) supported turbo-shaft. Contemporary solutions are hinged on structural modifications, which technology is saturated. Alternatively, this work presents the test-results for the effects of different feed-angles (Φ=0°−60°) on FRB rotordynamic stability behaviors across 6.0−30 krpm. The results indicate that the whirl frequency, orbit-size and sub-synchronous amplitudes are mitigated, particularly for large injection-angles. The pockets of pressure along the circumference minimize the asymmetries of pressure-fields, reduce destabilizing forces and enhance damping. However, supply-pressure must be optimized higher back-pressure at feedholes’ exits. Thus, it is concluded that angled-feedhole significantly improves FRB rotordynamic stability in high-performance turbo-systems.