Empirical correlation of heat generation in hybrid ball bearings, depending on the operational conditions in the aero-engine rotor supports

Abstract

Modern gas turbine bearings operate at high rotational speeds. Their speed index reaches dmn=3…3, 5-106 mmrpm, where dm = bearing mean diameter, and n = rotational speed. At high speeds, significant heat is generated in conventional steel bearings, and substantial cooling oil consumption may be required. A promising solution to this problem is using hybrid bearings with steel rings and ceramic rolling elements. Due to ceramic’s relatively small coefficient of thermal expansion, hybrid bearings retain radial clearance in a wide temperature range. Hybrid ball bearings, with an inner diameter of 130mm and 150mm, were tested in the bearings test rigs at the Central Institute of Aviation Motors (CIAM). From these tests, an empirical method for determining the thermal state of the bearings was developed. The calculated values correspond well with the experimental data presented in the extant literature.