Hybrid bearings for advanced aircraft engines

Abstract

High-speed rolling element bearings used in aircraft engines are custom-made components and operate under high temperature conditions owing to the elevated rotational speeds and loads. Therefore, assessing the various heat generation sources and mechanisms is worth investigating to accurately quantify the overall power loss within the bearing. In this context, a numerical parametric study was performed to determine and locate the various power losses inside an aero-engine cylindrical roller bearing. Then, a thermal network model based on Ohm’s law was developed in order to estimate the operation temperatures of the various bearing elements. A series of experimental test campaigns were also carried out under realistic operating conditions of load, speed, oil flow rate and oil supply temperature within a laboratory environment, to investigate and compare the thermal performances of two types of 90 mm bore cylindrical roller bearings: a hybrid bearing with silicon nitride (Si3N4) ceramic rollers, and an all-steel bearing (M50/M50Nil). The rig runs at speeds up to 30,000 rpm with the capability of applying radial loads up to 4500 N