Page 81 - Steam Turbines Design, Applications, and Rerating

62 Chapter Three

Figure 3.12 Pad-to-pad hot oil carryover and hot-cool oil mixing.
(RMT, Wellsville, N.Y.)

produced only marginal decreases in bearing operating temperature.
Two major problems associated with cooling a tilting-pad bearing are
illustrated in Fig. 3.12. Unfortunately, a substantial percentage of hot
oil is carried over by the journal from the trailing edge of the upstream
pad into the leading edge of the next downstream pad. Furthermore,
the cool inlet oil mixes with the discarded preceding pad’s hot oil before
it enters the downstream pad’s leading edge.
It was soon discovered that better results were achieved by applying
the cool inlet oil more effectively. One method of reducing the carryover
and hot-cool oil mixing is to introduce cool inlet oil directly into the
pad’s leading edge, as illustrated in Fig. 3.13. This effectively prevents

Figure 3.13 Leading-edge feed groove tilting-pad bearing design.
(RMT, Wellsville, N.Y.)