Thermal characteristics of a 90-mm bore cylindrical roller bearings for aerospace applications: All-steel versus hybrid bearings

Modern aircraft engines have to meet rigorous requirements such as thrust to weight ratio, efficiency and new regulations related to environment protection. These requirements affect all engine modules and components, including rolling element bearings. The latter have to withstand severe operating conditions because of the high thermal impact due to elevated rotational speeds and loads. In this study, two test campaigns were carried out under realistic operating conditions of load, speed, and oil flow rate to investigate and compare the thermal characteristics of two distinct cylindrical roller bearings: a hybrid bearing featuring silicon nitride (Si₃N₄) rollers and an all-steel bearing. Each bearing was instrumented with an array of thermocouples around its circumference to determine temperature profile under various test conditions. In addition, oil supply and drain temperatures were also measured to estimate the power loss. The experiments were conducted on a high-speed rolling-element test rig operating at speeds up to 30,000 rpm and under radial loads of up to 4500N.