Supervisors: Associate Professor Taeseong Kim, Senior Researcher Torben J. Larsen, Morten H. Hansen
External supervisors: Senior Researcher Christian Bak, DTU Wind Energy, PhD/Reader Rafael Palacios Nieto, Imperial College London, PhD/Advisory Engineer Bjarne Kallesøe, Siemens Wind Power
Abstract: Implementation of Passive Control Methodologies in the Preliminary and Conceptual Design of Wind Turbine Blades
This thesis deals with the development of methodologies for the implementation of passive control strategies in the preliminary and conceptual design process of a wind turbine blade. Reducing the cost of energy is a key concern for wind energy research and the ultimate goal for both academia and industry. An effective path to achieve this goal is to scale down the increase in total mass of the blades while designing rotors with increasing size and energy yield. In this context, the capability to mitigate loads on the structure during operation becomes an attractive characteristic for the design of modern wind turbine blades.
One of the family of methods for the alleviation of loads on a wind turbine is called passive control, as it relies on the idea of designing a structure that, without any active mechanisms, deforms so as to reduce the unsteady loading generated by turbulent fluctuating wind inflow. The concept behind passive control for wind turbine blades is to produce a structural coupling between flapwise bending towards the tower and torsion towards feathering. This coupling mitigates loads dynamically on the wind turbine structure due to a decrease in the angle of attack
Researchers have been fascinated by the possibility to embed a form of control directly into the structural design of a wind turbine blade for decades. A wind turbine rotor that can mitigate loads passively can be considered a cost effective solution because the load mitigation effects allow the employment of lighter components without the addition of actuators and mechanical actively-controlled parts. The load mitigation effects can be also used to stretch the size of the rotor, increasing the energy yield by the machine. If the passive-controlled wind turbine blade design process is formulated as an optimization problem using a multidisciplinary design optimization framework, the potential of passive control methods can be fully explored. From the application studies reported, we demonstrate how the integration of passive control as a design variable can open the path to the preliminary design of wind turbine rotors with not only considerable load alleviation potential, but also with substantially decreased blade mass or increased annual energy production.