Aeroelastic Rudder for a Wind Turbine

Abstract

An apparatus for yawing a turbine into the wind while reducing time-averaged loads has weight-balanced, aerodynamic fairings that cover structural elements of an offshore wind turbine. The aerodynamic fairings provide a rudder effect while a weight-balancing apparatus counters aeroelastic instability and buffers the effects of side gusts.

Claims

1. An aeroelastic rudder for a wind turbine comprising: a moored floating vessel having a plurality of non-vertical legs that support a wind turbine; and at least one axis of rotation, coaxial with said non-vertical legs, and engaged with said floating wind turbine; and an elongate, aerodynamic fairing having an upwind section and a downwind section, pivotally engaged between said upwind section and said downwind section, with said axis of rotation having a resting position coaxial with a wind prevailing direction; and at least one means to impart a restorative moment engaged with said elongate, aerodynamic fairing; wherein deflection of said aerodynamic fairing provides a restorative moment that returns said aerodynamic fairing to its resting position.

2. An aeroelastic rudder for a wind turbine comprising: a moored floating vessel having a plurality of non-vertical legs that support a wind turbine; and at least one axis of rotation, coaxial with said non-vertical legs, and engaged with said floating wind turbine; and an elongate, aerodynamic fairing having an upwind section and a downwind section, pivotally engaged between said upwind section and said downwind section, with said axis of rotation; and at least one weight in said upwind section of said elongate, aerodynamic fairing; wherein deflection of said aerodynamic fairing raises said weight, and falling of said weight opposes the deflection.

3. The aeroelastic rudder for a wind turbine of claim 2 further comprising: said moored floating wind turbine comprising a wide base supported by shallow draft floats; and said at least one axis of rotation resides along the center of a leg extending from a perimeter of said wide base to a point above said wide base supporting a wind-turbine rotor assembly; wherein the angle formed by said axis of rotation extends between said wide base and said wind-turbine rotor assembly forms said non-vertical axis.

4. The aeroelastic rudder for a wind turbine of claim 3 further comprising: said wide base being a parallelogram supported by at least one shallow draft float at each corner of said parallelogram; and four axes of rotation, each extending from one of the corners of the parallelogram to said point above said wide base; wherein at least two aerodynamic fairings are engaged with at least two of said four axes of rotation.

5. The aeroelastic rudder for a wind turbine of claim 4 wherein: said two aerodynamic fairings are engaged with two axes of rotation downwind of said wind-turbine rotor assembly.

6. The aeroelastic rudder for a wind turbine of claim 4 further comprising: a mooring hitch point engaged with said parallelogram midway between two corners.

7. An aeroelastic rudder for a wind turbine comprising: a moored floating wind turbine having a wide base that is a parallelogram, further comprising a mooring hitch point engaged with said parallelogram; and shallow draft floats supporting four corners of said parallelogram; and at least four legs, each extending from a corner of said parallelogram to a point above said parallelogram, each leg having a long, non-vertical axis; and at least two of said legs coaxial with said non-vertical axis; and at least two elongate aerodynamic fairings, each having an upwind section and a downwind section, each having an axis of rotation between said upwind section and said downwind section, pivotally engaged with said non-vertical axis; and at least one weight in said upwind section of each of said neutral aerodynamic fairings; wherein deflection of each of said aerodynamic fairings raises said weights, and falling of said weights opposes the deflection.

8. The aeroelastic rudder for a wind turbine of claim 7 further comprising: two weights in said upwind section of each of said neutral aerodynamic fairings; and at least one actuator movably engaged with said two weights; wherein said actuator moves said two weights in each neutral aerodynamic fairing with respect to said non-vertical axis to control the rotation of said two neutral aerodynamic fairings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a perspective view of an example embodiment with the rotor plane directed into the wind;

[0015] FIG. 2 is a cross-section, detail view thereof;

[0016] FIG. 3 is a cross-section, detail view of an iteration of the embodiment.

DESCRIPTION

[0017] In FIG. 1, an example embodiment 100 is an offshore wind turbine 110 having a rotor 116 and electrical-generation equipment 118. In an example embodiment, the wind turbine 110 is moored by mooring line 126 to a permanent structure on the seabed. A structural support system is made up of legs 112 and floats 114. Aerodynamic fairings 120 cover rear legs 112 (FIG. 2), and each pivot about an axis of rotation 122. Wind direction (prevailing wind direction) during normal operation is shown by arrow 140.

[0018] FIG. 2 is a detailed cross-section showing the internal components of the aerodynamic fairings 120. The aerodynamic fairing 120 is a form that rotates about an axis of rotation 122. A weight 124 is upwind of, and below, the axis of rotation 122. The position of the weight 124 provides force vectors 128. The forward vector 128 may be said to be in an upwind direction when the wind is blowing in the direction of arrow 140. The aerodynamic fairings 120 assist in aligning the turbine with the direction of the wind 140.

[0019] The aerodynamic fairings 120 counter the aeroelastic response of the structure to provide aerodynamic damping. The fairing 120 is rotatable about a pivot axis of rotation 122. The fairing 120, in combination with the weight 124, provides weight-balancing. In an example, a side gust may move the fairing 120, rotating it about axis of rotation 122. Axis of rotation 122 is at an angle from the vertical and so the weight 124 moves upward. As the weight 124 falls back to equilibrium the fairing 120 tends to move to a position that is perpendicular with the turbine rotor 116 and therefore in line with the wind direction 140. Acceleration to the left deflects the fairing 120 and raises the weight 124 to increase force to the right. Acceleration to the right deflects the fairing 120 and raises the weight 124 to increase force to the left. The passive action of the aerodynamic fairing 120 in combination with the weight 124 and the non-vertical axis of rotation 122 counters the dynamic amplification factor of forces on the structure.

[0020] In FIG. 3, an offshore wind turbine 210 has a rotor 216 and electrical-generation equipment 218. In an example embodiment, the wind turbine 210 is moored by mooring line 226 to a permanent structure on the seabed. A structural support system is made up of legs 212 and floats 214. Aerodynamic fairings 220 cover rear legs 212 and pivot about an axis of rotation 222. The wind direction during normal operation is shown by arrow 240.

[0021] In the iteration of the embodiment 200, overall weight is distributed by two weights 224 that are movable to a second position 224. Movement to the downwind side of the axis of rotation 222 will cause the aerodynamic fairing 220 to rotate as the weight falls below the pivot axis 222. By controlling the movement of the weights 224, the aerodynamic fairing 220 may be rotated to direct the turbine structure to respond to wind direction 240.

[0022] One skilled in the art understands that the pivoting aerodynamic fairing 120/220 may also be driven to provide an aerodynamic yaw mechanism. One skilled in the art further understands that a system may be operated by wireless technology to send and receive signals to and from control software and apparatuses to rotate the aerodynamic fairings 120/220, controlling the direction of the turbine 110/210 remotely.

[0023] These embodiments should not be construed as limiting.