Experimental assessment of gear meshing excitation propagation throughout multimegawatt gearboxes

Abstract

Gearboxes consisting of both planetary and helical gear stages are increasingly used in helicopters, wind turbines and vehicles. A requirement for reliable gearbox design calculations is sufficient insight in internal gearbox dynamics. Excitation frequencies and excitation levels play an important role. Main objective of this work is to investigate the influence of internal gear meshing excitation on the overall gearbox dynamics. Experiments are conducted on a dynamic 13.2MW test facility on which two multi-megawatt wind turbine gearboxes are placed back to back. A dedicated dynamic load case representing realistic drive train excitation is applied and the role of the meshing orders in spreading this excitation over a broader frequency range is determined by means of waterfall spectra from measurement signals of bearing displacement sensors, torque sensors, encoders and accelerometers throughout the gearbox. Moreover the propagation of the meshing excitation throughout the gearbox is of interest. Relating the orders to the corresponding excitation source allows the definition of order influence regions within the gearbox. These insights will be used to prove the need for accurate gear mesh order excitation representation within the corresponding flexible multibody simulation model. Moreover the meshing order influence regions offer the opportunity to tune order excitation to the gearbox modal properties and reduce vibration levels.status: publishe