Bearing Load Measurements on a 3-Shaft Gas Turbine
Axial location bearings are used to carry the load imbalance between the forward thrust of an aero-engine’s compressor and the rearwards drag of the turbine that drives the compressor’s rotation. The large gas turbines manufactured by Rolls-Royce have three independently rotating compressor/turbine stages, namely the low pressure (LP), the intermediate pressure (IP) and high pressure (HP) systems. The load imbalance, or bearing load, associated with each of these systems must be assessed during an engines development phase in order to confirm the reliability of the bearings throughout the operating life of the engine. The methods employed by Rolls-Royce to quantify the bearing loads on their modern range of gas turbines are discussed, including the most recent technique using modified engine structures to act as load measuring devices. Particular note is given to the instrumentation techniques used to record the loads generated by the engine during sea level testing.
L. P.J. Tipton "Bearing Load Measurements on a 3-Shaft Gas Turbine", Applied Mechanics and Materials, Vols. 1-2, pp. 225-232, 2004