Fluid Film Bearings Design Services

Computer programme was developed for the performance assessment of fluid film bearings supporting vertical Hydro-machine and vertical pumps.The effect of thermal and elastic distortion of the thrust bearing surface on the Hydrodynamic oil film at the interface, is illustrated graphically. The flow chart of the computer programme is enclosed in two parts. The programme is valid for thrust bearing assemblies supported by rigid ring pivots in the bearing assembly as illustrated in Figures 2 and 3. Axial layout of a typical Hydro machine is given below.
ANALYSIS
The temperature spectrum for Poringalkuthu Hydro generator shows an alarming increase in the thrust bearing temperature of 95 degrees during Runaway speed of the machine, when compared to 75 degrees for Normal speed. The Distortion-effects of the thrust bearing, on the oil film availability, is clearly shown. Here is a case worth examining, for a better heat-transfer from the thrust bearing, by Direct-cooling methods, to avoid the increase of temperature beyond 75 degrees. We can also think of installing a means to monitor the availability of oil film thickness and measure the same, during operation of the machine. An on- line method of visualizing and measuring the oil film thickness, in hydrodynamic thrust bearing, of Hydro generators is discussed here. It consists of inserting a metal shim of known thickness, along the inner edge, of the thrust bearing segment, flush with the radius of curvature of the inner edge of the bearing pad. This enables viewing the shim at the same time examining the oil film availability separating the bearing pad from rotating thrust collar. Suitable see- through mirror window at vantage point, on the inner wall of the oil pot, enable viewing this phenomenon from outside, without interfering with the machine operation. This is illustrated in the figure separately.The Computer programe was run for runaway speeds on cam and off cam. The computer out put showing important performance parameters like bearing power loss, oil film thickness, heat carried by the oil, radial forces for different speeds etc, wereillustrated graphically for easy reading.Increase in power loss and bearing temperature was noticed for the three speeds of operation of the machine. Corresponding reduction in oil film thickness was noticed, to indicate introduction of a means to control this excessive temperature rise during runaway speeds of operation of the machine.