Thrust
Collars for Integrally Geared Compressors
MAJOR APPLICATION: Cost effective axial load
support in rotating machinery (typically integrally geared compressors)
Sponsor: Samsung Techwin
(2012-2014)
OBJECTIVE: To evaluate the hydrodynamic
pressure and force coefficients in the thin film between the thrust collar and
bull gear taper.
Significance: Typically thrust collars are
implemented in integrally geared compressors to absorb the axial load on the
pinion shaft (see Fig. 1). This provides a cost effective and efficient means
of balancing the thrust load created by the compressor or expander stages on
either side of the pinion gear. These thrust collars (sometimes referred to as rider rings) act as hydrodynamic
bearings transferring the axial load to the bull gear shaft, on which there is
a large diameter thrust bearing to absorb the thrust in the compressor.
Fig. 2 shows a top view of the
lubricated zone between the thrust collar and the bull gear. The lubricant in
this region develops hydrodynamic pressure, governed by Reynolds equation. The
thin film also has associated force coefficients (stiffness and damping).
Fig
1. Cut view of a four stage integrally geared
compressor.
Fig. 2. Schematic
view of the fluid film between the bull gear taper and the thrust collar.