An Experimental Study of Thrust Pad Flutter

Abstract

Tilting pad thrust bearings are commonly used on both the active and inactive (loaded and unloaded) sides of thrust collars of turbomachinery rotors. Fatigue failure of temperature sensor leadwires to the inactive side thrust pads and abnormal wear at contact points of these thrust pads, in several field applications, led to an investigation as to the cause. Since these problems occurred only on “unloaded” thrust bearings, flutter (vibration) of these inactive side thrust pads was suspected. Tests were run in the laboratory on a double thrust bearing under conditions simulating a turbomachine application. Pad flutter was found at two distinct conditions; low oil flows (as suspected), and also at high oil flows. The paper presents the results of these tests with data on the influence of the parameters studied, and the findings with respect to elimination of this flutter.