Assessment of noise attenuating powertrain components

Wind turbine noise used to be dominated by aerodynamic blade noise, effectively masking mechanical noise, originating from the drivetrain. Successful blade noise reduction makes mechanical noise audible. Resonances can cause annoying tonalities which hardly can be avoided with standard measures. The basic idea is to get down to the root cause of the problem: Excitations are being mitigated at its source in order to avoid the formation of structure born sound, rather than trying to dampen the propagation of noise at any location of the transfer path through the drivetrain structure. Powertrain components (torsional dampers and torsional elastic couplings) used for many decades to reduce torsional vibrations of combustion engines, are also being applied since a while to reduce mechanical engine noise, by dampening torsional vibrations of the camshaft caused by excitations of the injection pump [1]. An assessment of such technologies integrated to a wind gearbox by applying torsional vibration calculations (TVC) is main objective of this paper.