Determination of the Area of Rational Use of Hybrid Bearings With Steel Rings and Ceramic Rolling Elements in High-Speed Aircraft Engines

Abstract

Abstract The process of improving gas turbine engines is associated with increased thermodynamic parameters and rotor speed. In advanced aircraft engines the main rotor bearings will operate at speed index dmn > 3 · 106 mm · rpm, where dm is the bearing pitch diameter (mm), and n is the rotational speed (rpm). Under these conditions, significant heat is generated in the bearings, and the use of hybrid rolling bearings with steel rings and ceramic rolling elements looks more attractive due to the ceramic’s low density and low coefficient of thermal expansion. A computational method for predicting the thermal state of rolling bearings operating at high speed parameters has been developed based on comparative tests of steel and hybrid rolling bearings. Knowing the thermal state of the bearing allows the value of the operating clearance to be set in the bearing, which is important for determining the contact angle and load distribution over the rolling elements. A comparison with the results from tests of hybrid and steel bearings presented in the previous literature has shown that the calculated values correspond to the experimental data. Criteria for selecting steel or hybrid bearings are proposed, and areas of rational use for hybrid rolling bearings in aircraft engines are determined.