Tilting pad fluttering in bearings for high-performance turbomachinery can cause severe problems such as bearing damage and rotor vibrations. Difficult to predict, tilting pad fluttering incidents often result in time-consuming repairs and bearing modifications. Through extensive testing, the team at MIBA Bearings has developed new bearing designs that can reliably prevent the occurrence of tilting pad fluttering.
Troubleshooting repairs are costly
There’s more art than science involved in today’s methods to prevent tilting pad fluttering. Common solutions include flooding the bearing lubrication and restricting the range of the pad preload.
Different solutions are used if problems occur after the machine is put into operation, such as changes to the bearing oil supply, or the (costly) reworking of affected pads. In addition to the effort involved, these solutions can impact equipment, amount of oil required, or rotordynamic properties of the bearings.
Troubleshooting bearing issues? Download this handy bearing inspection guide. Click here.
Investigating Tilting Pad Fluttering
The R&D team at MIBA investigated the occurance of tilting pad fluttering using a Ø120 mm test bearing (with directed lubrication, evacuated housing, and spherical pad support). A displacement sensor was used to monitor the distance between the bearing housing and one unloaded pad.
Testing demonstrated tilting pad fluttering occurred reproducibly at sliding speeds of 60 m/s, and above, when certain bearing loads were exceeded.
Elastic pad fixation
MIBA’s solution to prevent tilting pad fluttering consists of an elastic fixation attaching unloaded pads to the bearing housing. The elastic prevents radial pad lift-off and stabilizes the usual tilting behavior of the pads.
The effectiveness of this solution was confirmed by extensive additional tests. For more on the elastic pad fixation solution, download the full whitepaper: CLICK HERE
Related article: Gas Turbine Bearings: an overview
About Miba: Miba Industrial Bearings designs, repairs and manufactures hydrodynamic bearings and labyrinth seals for use in high-performing rotating equipment, such as turbines, compressors or generators. Miba started manufacturing bearings in 1949 and brings a rich history of engineering excellence as a leading partner for the gas and steam turbine industry.
