Wind Turbine With Aerodynamic Fairings

Abstract

An apparatus for aligning flow entering a turbine rotor, and for straightening flow in the wake of a turbine rotor, is, in some embodiments, part of a structure that supports a nacelle and a turbine rotor. Neutral airfoil fairings on structural elements upwind of a rotor can mitigate the effect of side gusts and help straighten the flow entering a rotor. Neutral airfoil fairings on structural elements placed downwind of a rotor straighten turbulent flow in a turbine wake and increase the rate at which the wake dissipates. This enables increased energy extraction at the rotor as well as closer spacing of turbines in a field.

Claims

1. An aerodynamic fairing for a wind turbine comprising: a moored floating wind turbine having at least two non-vertical shafts supporting a rotor and generator; and said rotor having a central axis and a rotor plane surrounding said central axis; and said non-vertical shafts each having long central axis; and at least one elongate aerodynamic fairing having a long central axis, a lift surface and a pressure surface, engaged coaxially with at least one of said at least two non-vertical shaft central axis; and said lift surface on said at least one elongate aerodynamic fairing faces the rotor central axis; wherein airflow over said lift surface is directed into said rotor plane providing increased mass flow through said rotor plane.

2. The aerodynamic fairing for a wind turbine of claim 1 further comprising; said at least one elongate aerodynamic fairing pivotally engaged with said at least two non-vertical shafts about said aerodynamic fairing central axis and said coaxial non-vertical shaft central axis; wherein off-axis gusts are turned to a direction that is parallel with said rotor central axis.

3. The aerodynamic fairing for a wind turbine of claim 1 further comprising: said moored floating wind turbine having at least two non-vertical shafts supporting a rotor and generator, upwind of said rotor and generator, and at least two non-vertical shafts supporting a rotor and generator downwind of said rotor and generator; and said at least one elongate aerodynamic fairing is engaged with each of said at least two upwind non-vertical shafts and at least one elongate aerodynamic fairing is engaged with each of said at least two downwind non-vertical shafts; wherein said upwind aerodynamic fairings direct wind into said rotor plane and said downwind aerodynamic fairings cause increased suction through said rotor plane and introduce high-speed air into a rotor wake.

4. An aerodynamic fairing 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 shafts, each having a long central axis and each extending from a corner of said parallelogram to a rotor and a generator located above said parallelogram; and said rotor having a horizontal, central axis and a rotor plane surrounding said horizontal, central axis; and at least two of said at least four shafts, upwind of said rotor and generator, and at least two of said at least four shafts, downwind of said rotor and generator; at least four elongate aerodynamic fairings, each having a long central axis, a lift surface and a pressure surface, engaged coaxially with said at least four shafts long central axis; wherein said upwind aerodynamic fairings direct wind into said rotor plane, and said downwind aerodynamic fairings cause increased suction through said rotor plane and introduce high speed air into a rotor wake.

5. A neutral aerodynamic fairing for a wind turbine comprising: a moored floating wind turbine having at least two non-vertical shafts supporting a rotor and generator; and said rotor having a central axis and a rotor plane surrounding said central axis; and said non-vertical shafts each having long central axis; and at least one elongate neutral aerodynamic fairing having a long central axis, engaged coaxially with at least one of said at least two non-vertical shaft central axis; wherein airflow over said at least one elongate neutral aerodynamic fairing is straightened while being directed into said rotor plane.

6. The neutral aerodynamic fairing for a wind turbine of claim 5 further comprising: said at least one elongate neutral aerodynamic fairing pivotally engaged with said at least two non-vertical shafts about said aerodynamic fairing central axis and said coaxial non-vertical shaft central axis; wherein off-axis gusts are turned to a direction that is parallel with said rotor central axis.

7. The neutral aerodynamic fairing for a wind turbine of claim 5 further comprising: said moored floating wind turbine having at least two non-vertical shafts supporting a rotor and generator, upwind of said rotor and generator, and at least two non-vertical shafts supporting a rotor and generator downwind of said rotor and generator; and said at least one elongate neutral aerodynamic fairing is engaged with each of said at least two upwind non-vertical shafts and at least one elongate neutral aerodynamic fairing is engaged with each of said at least two downwind non-vertical shafts; wherein said upwind neutral aerodynamic fairings straighten and direct wind into said rotor plane, and said downwind neutral aerodynamic fairings straighten wind in a rotor wake.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a perspective view of an example embodiment with the rotor plane directed into the wind;

[0016] FIG. 2 is a cross-section, detail view thereof;

[0017] FIG. 3 is an iteration of the embodiment.

DESCRIPTION

[0018] In FIG. 1 an example embodiment 100 is an offshore wind turbine 110 having a rotor 116 and electrical-generation equipment 118. The rotor 116 rotates about a horizontal axis at its center. The area covered by the rotating rotor 116 is referred to as a rotor plane. In an example embodiment, the wind turbine 110 is moored by a line 126 to a permanent structure on the seabed. Towers 113 and floats 114 form a structural support system. It may be said that the towers 113, also referred to as shafts 113 are non-vertical, as they reside at an angle between floats 114 to electrical-generation equipment 118. Neutral aerodynamic fairings 112 cover front towers 113. Towers 113 and rear towers may also be referred to as shafts. Rearward, neutral, aerodynamic fairings 120 cover rear towers. It may be said that a long central axis of the aerodynamic fairings 120 are parallel with the long central axis of the towers 113 that they cover. One skilled in the art is familiar with structural supports 113 and understands how similar support structures may be enclosed by neutral aerodynamic fairings 120. Wind direction during normal operation flows perpendicular to the rotor plane, parallel to the rotor central axis, and is shown by arrow 140. One skilled in the art understands that objects in front of the rotor may be said to be upwind of the rotor and objects behind the rotor may be said to be down wind of the rotor.

[0019] FIG. 2 is a cross-section showing the aerodynamic cross-sections of fairings 112 and 120. The aerodynamic fairing 112 is a substantially symmetrical form that aligns a portion of the wind stream 140 through a rotor 116. In some examples, off-axis or side gusts 141 are momentary winds not aligned with a prevailing stream 140 encountering a turbine 110. The forward aerodynamic fairings 112 help align the wind with the rotor 116 to turn side gusts into the prevailing-stream direction 140. Rear aerodynamic fairings 120 help straighten the turbulent flow 143 in the wake. Straightened wake flow may help dissipate the wake, relieving the effect of an impediment in the fluid stream, enabling more mass flow through the rotor, and greater energy extraction. Resulting, faster wake-dissipation may allow turbines in a field to be spaced closer together than those without flow-straightening aerodynamic fairings 120.

[0020] FIG. 3 is a cross-section of an iteration 200 showing the aerodynamic cross-sections of fairings 212 and 220. The aerodynamic fairing 212 is an airfoil form with the lift surface facing the rotor center. The lift over the airfoil draws a relatively wider portion of the wind stream 240 through the rotor 216. Flow stream 241 demonstrates additional mass flow drawn into the prevailing stream 240 encountering the rotor 216. Rear aerodynamic fairings 220 draw flow that would have otherwise bypassed the rotor through the rotor plane and help straighten the turbulent flow in the wake. Reference numbers 210 and 218 show the same parts as like numbers in iteration 100.