High performance at low to medium wind speeds is the USP for Siemens new low-noise version of its 3.3 MW unit, which has been designed specifically for noise restricted sites. Designated SWT-3.3-130LN, the turbine operates at a reduced rotor speed compared to its progenitor the SWT-3.3-130, and includes aerodynamic modifications to its rotor blades. Utilising these ‘add-ons’, it can be operated at a noise level of 104.9 dB. It is scheduled to go into commercial production in early 2017.

The fast air stream passing the tips of the rotor is primarily responsible for the characteristic noise of a wind turbine in operation. This is curtailed in the new turbine with its aero- acoustic optimisation of the B63 blades, allowing what Siemens says is silent operation. In addition to vortex generators on the blade surface, trailing edges are equipped with a combination of serrations and combs, known as the ‘DinoTail Next Generation’. Each comb tooth element creates fine vortices at the point where the fast air stream from above the blade profile meets the slower air stream flowing below. As a result, the aerodynamic noise from the trailing edge of the blade is reduced significantly. The result is high performance at low rotor speed. This enables the LN version to reach a maximum rating of 3.3 MW with a noise emission reduced by nearly two decibels compared to the SWT-3.3-130 launched in 2014.

The SWT-3.3-130LN wind turbine represents a combination of established Siemens direct drive technology and cutting edge aerodynamics. Even at an average wind speed of 6.5 m/s, it is capable of an annual energy production of around 11 GWh. At 8.5 m/s, the AEP reaches 16 GWh.