59872 - Determination of the Area of Rational Use of Hybrid Bearings With Steel Rings and Ceramic Rolling Elements in High-Speed Aircraft Engine 

The process of improving gas turbine engines is associated with an increase in thermodynamic parameters and rotor speed. In advanced aircraft engines the main rotor bearings will operate at speed index ​​d­_mn> 3 ∙ 10⁶ mm ∙ rpm, where d_m is the bearing mean diameter (mm), 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 low coefficient of thermal expansion and low density of the ceramic. Based on comparative tests of steel and hybrid rolling bearings, CIAM has developed a computational method for predicting the thermal state of rolling bearings operating at speed parameters up to 3.5 ∙ 10⁶ mm ∙ rpm. A comparison with the results of the tests of hybrid and steel bearings presented in the literature showed that the calculated values correspond to the experimental data. The developed method makes it possible to determine heat generation, the temperature of the inner and outer rings, depending on the operating conditions of the bearing in the support. Knowledge of the temperature bearing allows you to determine the definition of the operational clearances in the bearing, which is important for the contact angle and load distribution over the rolling elements. Criteria for the selection of steel or hybrid bearings are proposed, and the area of ​​rational use of hybrid rolling bearings in aircraft engines is determined.