Wind turbine noise measurements and abatement methods - Wind Power Generation and Wind Turbine Design - page 655

Figure 11: Background and operation noise measurements for a small wind
turbine [ 17 ].
proposed erection of a wind farm. Among others, it assesses how the proposed
wind farm will effect the environment and the public health, and whether any
resultant changes in conditions are deemed acceptable or unacceptable. Best code
guidelines and policy standards are being practised and followed in order to ensure
environmental protection including noise and nuisance.
Recalling that the type of noise generated from a wind turbine can be mechanical
and aerodynamic, we are able to investigate and fi nd solutions for noise treatment.
Starting with the mechanical parts of a wind turbine that rotate or move in rela-
tion to each other such as gears that are creating structure-borne noise and vibra-
tion, it becomes clear about the need for designing gearboxes for quiet operation.
Wind turbines use special gearboxes, in which the gear wheels are designed
slightly fl exible in order to reduce mechanical noise. One way of doing this is to
ensure that the steel wheels of the gearbox have a semi-soft, fl exible core, but a
hard surface to ensure strength and long time wear.
In addition to designing quiet parts, insulating those parts seems to be another
way to tackle that type of noise. Soundproofi ng and mounting equipment on sound
dampening buffer pads helps to deal with this issue. In addition, special sound
dampening buffer pads separate the gearboxes from the nacelle frame to minimise
transmission of vibrations to the tower
There are limited acoustic solutions that can be applied to reduce noise from the
mechanical movements due to the space restriction inside the nacelle as well as the
necessity not to disturb the effi cient functionality of the mechanical parts with
added acoustic treatment. Although for large wind turbines mechanical noise is not