The lengths and/or chords and/or pitches of wind turbine or propeller blades are individually established, so that a first blade can have a length/chord/pitch that is different at a given time to the length/chord/pitch of a second blade to optimize performance and/or to equalize stresses on the system.

The present invention relates to a method for operating a wind turbine (1). The wind turbine (1) comprises one or more wind turbine blades (5), each wind turbine blade (5) being connected to a blade carrying structure (4) mounted on a hub (3), via a hinge (6) at a hinge position of the wind turbine blade (5), each wind turbine blade (5) thereby being arranged to perform pivot movements relative to the blade carrying structure (4) between a minimum pivot angle and a maximum pivot angle. The method comprises the steps of detecting an airborne object entering a predefined zone around the wind turbine (1), comparing a current tip height (H) of the wind turbine (1) to a maximum tip height value, the maximum tip height value representing a maximum allowable tip height under currently prevailing conditions. In the case that the current tip height (H) exceeds the maximum tip height value, a pivot angle (P) of wind turbine blades (5) is adjusted in order to decrease the tip height (H) of the wind turbine (1) to a value below the maximum tip height value.

A wind turbine (1) comprising a tower (2), a nacelle (3) and a hub (7) is disclosed. The hub (7) comprises a blade carrying structure (4) with one or more wind turbine blades (5) connected to thereto. Each of the wind turbine blades (5) defines an aerodynamic profile having a thickness which varies along a length of the wind turbine blade (5). Each of the wind turbine blades (5) is connected to the blade carrying structure (4) via a hinge (6) at a hinge position of the wind turbine blade (5), each wind turbine blade (5) thereby being arranged to perform pivot movements relative to the blade carrying structure (4) between a minimum pivot angle and a maximum pivot angle. The hinge position is arranged at a distance from the inner tip end (5a) and at a distance from the outer tip end (5b), and the thickness, or the thickness-to chord ratio, at the hinge position is larger than the thickness, or the thickness-to-chord ratio, at the inner tip end (5a) and larger than the thickness, or the thickness-to-chord ratio, at the outer tip end (5b).

A wind turbine blade comprises a flexible external skin and an internal support structure, together defining an aerodynamic profile of the wind turbine blade. At least a portion of the internal support structure is adjustable to thereby vary the aerodynamic profile.

Provided is an adaptable spoiler for a wind turbine rotor blade, including: a base element adapted to be connected at or integrated with a rotor blade; an airfoil element being attachable to the base element and having an airfoil shaped surface to be exposed to an air flow.

Provided is an adaptable spoiler for a wind turbine rotor blade, including: a base element adapted to be connected at or integrated with a rotor blade; an airfoil element being attachable to the base element and having an airfoil shaped surface to be exposed to an air flow.

A lift control device actively controls the lift force on a lifting surface. The device has a protuberance near a trailing edge of its lifting surface, which causes flow to separate from the lifting surface, generating regions of low pressure and high pressure which combine to increase the lift force on the lifting surface. The device further includes a means to keep the flow attached around the protuberance or to modify the position of the protuberance in response to a command from a central controller, so as to provide an active control of the lift between a maximum value and a minimum value.

A horizontal axis wind turbine (1) with a wind turbine blade (5) is disclosed, the wind turbine blade (5) comprising a hinge (6) arranged to connect the wind turbine blade (5) to a blade carrying structure (4) of the wind turbine (1), at a non-zero distance from an inner tip (5a) and at a non-zero distance from an outer tip (5b) of the wind turbine blade (5). An outer blade part (7) is arranged between the hinge region and the outer tip (5b), and an inner blade part (8) is arranged between the hinge region and the inner tip (5a). The outer blade part (7) extends from the hinge region along a first direction and the inner blade part (8) extends from the hinge region along a second direction, and the first direction and the second direction form an angle, α, there between, where 0°<α<90°.

The present invention relates to wind energy and can be used to harvest and convert kinetic wind energy into electricity with higher efficiency.

Wind turbine that improves the efficiency of converting wind energy into electrical energy by implementing mechanical design features which harness the entrainment effect by using main rotor blades that are mounted at some distance from the center axis of rotation to allow airflow to pass through its center and to be accelerated by any means (jet fan for example), thus creating higher velocity lower pressure air stream (according to Bernoulli’s law) behind the wind turbine increasing airflow (entrainment effect) through the main rotor blades.

The invention as claimed is a lift-based horizontal-axis wind turbine, the design of which provides higher performance efficiency by extracting more energy from the airflow and at better coefficient of performance and converting it into electrical energy, compared to conventional lift-based horizontal-axis wind turbines of the same turbine rotor diameter.

Described is a system for monitoring deflection of turbine blades of a wind turbine comprising a tower. The system comprises a position detecting apparatus mounted to the wind turbine, the position detection apparatus comprising position detection components each detecting a presence or absence of a corresponding one of the segments of the turbine blades; and a deflection controller configured to receive the presence or absence detection and to use the presence or absence detection to determine a distance of each of the segments of the turbine blades relative to the tower, whereby the distance of each of the segments of the turbine blades relative to the tower is representative of the deflection of the turbine blades.