Dynamic Performance Characteristics of Floating-Ring Bearings with Varied Oil-Injection Swirl-Control Angles

Title
Dynamic Performance Characteristics of Floating-Ring Bearings with Varied Oil-Injection Swirl-Control Angles
Authors
다니엘 타무노김창호이용복
Keywords
Floating-ring bearing; dynamic coefficients; analytical modelin; oil-bearing
Issue Date
2015-02
Publisher
Journal of dynamic systems, measurement, and control
Citation
VOL 137, NO 2, 021002-1-021002-11
Abstract
Hydrodynamic instabilities are prime causatives of performance irregularities and violent vibrations in floating-ring bearing (FRB) supported turbo-systems. In the quest for energy-efficient solutions, researchers have evolved several design geometries, dimensional relationships and surface-contours for the FRBs. Unfortunately, the analytical results of these modifications lack sufficient test-data to benchmark their authenticities. Consequently, this work advances an innovative concept and the test results of flow redirection in FRBs, using an oil-injection swirl-control mechanism (OJSCM) to attenuate instabilities in high-performance rotor-bearing systems. FRBs with radius-ratio = 1.75 and clearance-ratio = 1.5 are tested for various OJSCM injection-angles (0°, 30°, 60°) and under a static-load of 50 N. The test results indicate that OJSCM produces substantial improvements in FRB-damping and stability characteristics. The whirl-frequency-ratio and cross-couple forces are diminished due to improved symmetry of films' pressure-forces (Kxx ≈ Kyy). Although the magnitudes of direct damping are higher (; Cxx; is 16.92 kNs/m for 60° and 6.03 kNs/m for 0°), the load capacity (Kxx) is slightly lower than the normal (0°), injection. This discrepancy in load capacities is insignificant for high-speed operations because they tend to converge at 3.5 MN/m. Furthermore, the whirl-frequency-ratio and sub-synchronous amplitudes, which are graphic reflections of the bearing-based instabilities, become progressively smaller with increasing OJSCM angle. However, this advantage at elevated speeds can only be sustained by a corresponding increase in oil-supply pressure. A starved inner film aggravates imbalance response and thermal growth. In closure, the advanced anti-swirl oil-injection mechanism is effective for mitigating rotordynamic instabilities in high-speed rotor-bearing systems for turbomachinery applications.
URI
http://pubs.kist.re.kr/handle/201004/47887
ISSN
15289028
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KIST Publication > Article
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