Danish blade maker LM Wind Power and the Energy Research Centre of the Netherlands (ECN) have developed blade tips which are said to increase offshore wind farm yields.
“The design of an offshore turbine blade requires a different way of thinking for two reasons,” said Ozlem Ceyhan-Yilmaz of ECN.
“Firstly, there are fewer limitations to noise emission because there are no people living nearby. Secondly, the offshore challenge is to design rotors that will result in the largest power output for complete wind farms.”
To influence the wake behind the turbine, ECN and LM Wind Power designed a special tip for integral optimisation of turbines without considering noise limitations.
ECN has also developed a wake reduction tip with a zigzag shape which is said to increase turbulence in the boundary of the wake which increases the yield of offshore wind farms.
These designs were validated on 2.5MW-sized wind turbines at ECN’s wind turbine test facility in the Wieringermeer.
“This demonstration was unique. A full-scale experiment in an operating wind farm was performed. Then tips were installed on the blades of the wind turbines in such manner that they could be removed afterwards. The method for installation and removal has been an innovation by itself, and required close cooperation between ECN and LM Wind Power,” Ozlem said.
The results of the test at these 80m large rotor blades demonstrated that an increased farm power output up to six percent is achievable through blade tips. By using a new method, ECN made it possible to measure relatively small power increases.
“Great results are encouraging to continue designing models and demonstrating blade tips. Together we aim to lower costs of wind energy,” Ozlem said.