# US 11,028,822 B2 · Wind turbine airfoil structure for increasing wind farm efficiency > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,822 B2 - Document ID: US11028822B2 - Status: Granted - Kind: B2 - Application number: 16/288,976 - Filed: 2019-02-28 - Published: 2019-12-19 - Granted: 2021-06-08 - Earliest claimed: 2018-06-19 - Assignees: University of Massachusetts - Applicants: University of Massachusetts - Inventors: Shujaut Bader; Blair Perot - Web page: https://patentgrep.com/patent/US11028822B2 ## CPC - F03D 1/04: having stationary wind-guiding means, e.g. with shrouds or channels (F03D9/35 takes precedence) - F03D 80/80: Arrangement of components within nacelles or towers - F05B 2240/13: to collect or cause flow towards or away from turbines - F05B 2240/96: as part of a wind turbine farm - F05B 2270/204: taking into account the wake effect - Y02E 10/72: Wind turbines with rotation axis in wind direction - F03D: WIND MOTORS - F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A wind turbine comprises a nacelle, a drive shaft extending from the nacelle along a shaft axis, a plurality of turbine blades coupled to the drive shaft and extending radially relative to the shaft axis, and a first static airfoil structure coupled to the wind turbine to influence airflow exiting the plurality of turbine blades. A method of increasing wind turbine efficiency in a wind farm comprises positioning a first wind turbine having a first plurality of turbine blades at least partially upstream of a second wind turbine having a second plurality of turbine blades, producing a wake field of exit air behind the first plurality of turbine blades, directing air outside of the wake field into the wake field to increase speed of airflow in the wake field, and directing the airflow into the second plurality of turbine blades of the second wind turbine. ## Claims ### Claim 1 A wind turbine comprising: a nacelle; a drive shaft extending from the nacelle along a shaft axis; a plurality of turbine blades coupled to the drive shaft and extending radially relative to the shaft axis; and a first static airfoil structure coupled to the wind turbine to influence airflow exiting the plurality of turbine blades; wherein the plurality of turbine blades are configured to generate a wake field; wherein the first static airfoil structure is configured to push wake field air toward ground level; and wherein a majority of a span of the first static airfoil structure is configured to push wake field air toward ground level. ### Claim 2 (depends on 1) The wind turbine of claim 1, wherein the first static airfoil structure is static relative to the nacelle. ### Claim 3 (depends on 1) The wind turbine of claim 1, wherein the first static airfoil structure is positioned radially outward of the plurality of turbine blades. ### Claim 4 (depends on 1) The wind turbine of claim 1, wherein: each of the plurality of turbine blades includes an inner end portion connected to the drive shaft and an outer tip portion; and the first static airfoil structure is positioned radially inward of the distal tip portions of the plurality of turbine blades. ### Claim 5 (depends on 1) The wind turbine of claim 1, wherein: each of the plurality of turbine blades includes a leading edge and a trailing edge, and the nacelle is positioned aft of the trailing edge; and the first static airfoil structure is positioned axially aft of the plurality of turbine blades. ### Claim 6 (depends on 1) The wind turbine of claim 1, wherein: the nacelle defines an inboard side and an outboard side, the wind turbine further comprising a mounting shaft extending from the inboard side of the nacelle along a longitudinal axis; and the first static airfoil structure is supported by the nacelle. ### Claim 7 (depends on 6) The wind turbine of claim 6, wherein the first static airfoil structure is mounted outboard of the nacelle such that the first static airfoil structure is positioned radially outward of the plurality of turbine blades. ### Claim 8 (depends on 6) The wind turbine of claim 6, wherein the first static airfoil structure is mounted inboard of the nacelle such that the first static airfoil structure is positioned radially inward of the plurality of turbine blades. ### Claim 9 (depends on 6) The wind turbine of claim 6, further comprising a second static airfoil structure supported by the nacelle to influence airflow exiting the plurality of turbine blades, wherein the first static airfoil structure and the second static airfoil structure are each configured to push wake field air toward ground level to allow wake field air to be displaced by faster moving air located outside the wake field. ### Claim 10 (depends on 9) The wind turbine of claim 9, wherein the first and second static airfoil structures are positioned longitudinally apart from each other on opposite sides of the nacelle. ### Claim 11 (depends on 1) The wind turbine of claim 1, wherein the first static airfoil structure comprises an airfoil comprising: a leading edge for facing in an upwind direction; a trailing edge for facing in a downwind direction; a pressure side extending between the leading and trailing edges; and a suction side extending between the leading and trailing edges; wherein the suction side faces the plurality of turbine blades. ### Claim 12 (depends on 11) The wind turbine of claim 11, wherein the first static airfoil structure is arcuate along a span extending between ends of the first static airfoil structure. ### Claim 13 (depends on 12) The wind turbine of claim 12, wherein the first static airfoil structure has an angle of attack of fifteen degrees relative to the shaft axis. ### Claim 14 (depends on 13) The wind turbine of claim 13, further comprising a mechanism to adjust the angle of attack. ### Claim 15 (depends on 1) The wind turbine of claim 1, wherein the first static airfoil structure comprises a metal structure mounted to the nacelle by a plurality of struts. ### Claim 16 (depends on 1) The wind turbine of claim 1, wherein the first static airfoil structure comprises: a rigid frame structure and a skin at least partially covering the rigid frame structure; and a furling mechanism for furling and unfurling the skin. ### Claim 17 A method of increasing wind turbine power efficiency in a wind farm, the method comprising: positioning a first wind turbine having a first plurality of turbine blades at least partially upstream of a second wind turbine having a second plurality of turbine blades; producing a wake field of exit air behind the first plurality of turbine blades; directing air outside of the wake field into the wake field to increase speed of airflow in the wake field by pulling air into the wake field using an airfoil structure to displace some of the exit air in the wake field with faster moving air from air outside of the first plurality of turbine blades; and directing the airflow including the faster moving air into the second plurality of turbine blades of the second wind turbine; wherein the airfoil structure does not affect performance of the first wind turbine. ### Claim 18 (depends on 17) The method of claim 17, further comprising: mounting the first wind turbine to a tower; and attaching a static airfoil structure to a nacelle of the first wind turbine. ### Claim 19 (depends on 17) The method of claim 17, wherein the faster moving air is located outboard of the first plurality of turbine blades. ### Claim 20 (depends on 17) The method of claim 17, wherein the faster moving air is located laterally of the first plurality of turbine blades. ### Claim 21 (depends on 17) The method of claim 17, further comprising adjusting the static airfoil structure to reduce drag in wind conditions. ### Claim 22 (depends on 21) The method of claim 21, further comprising adjusting an angle of attack to reduce drag. ### Claim 23 (depends on 21) The method of claim 21, further comprising furling a skin of the airfoil structure to reduce drag. ### Claim 24 (depends on 1) The wind turbine of claim 1, further comprising a second static airfoil structure supported by the nacelle to influence airflow exiting the plurality of turbine blades, the first and second static airfoil structures each comprising: a leading edge for facing in an upwind direction; a trailing edge for facing in a downwind direction; a pressure side extending between the leading and trailing edges; and a suction side extending between the leading and trailing edges; wherein the pressure sides both face toward a groundward direction. ### Claim 25 (depends on 24) The wind turbine of claim 24, wherein: the first static airfoil structure and the second static airfoil structure are arcuate along a span extending between ends of the first and second static airfoil structures and are positioned radially outward of the plurality of turbine blades; the first static airfoil structure is positioned above the plurality of turbine blades and extends along less than fifty percent of a circumference of the wind turbine; and the second airfoil structure is positioned below the plurality of turbine blades and extends along approximately fifty percent of the circumference of the wind turbine. ### Claim 26 (depends on 17) The method of claim 17, wherein the static airfoil structure is configured to not directly mix the faster moving air with the exit air. ### Claim 27 A wind turbine comprising: a nacelle that defines an inboard side and an outboard side; a mounting shaft extending from the inboard side of the nacelle along a longitudinal axis; a drive shaft extending from the nacelle along a shaft axis; a plurality of turbine blades coupled to the drive shaft and extending radially relative to the shaft axis; and a first static airfoil structure coupled to the wind turbine to influence airflow exiting the plurality of turbine blades, the first static airfoil structure being supported by the nacelle; wherein the plurality of turbine blades are configured to generate a wake field; wherein the first static airfoil structure is configured to push wake field air toward ground level; and wherein the first static airfoil structure is mounted outboard of the nacelle such that the first static airfoil structure is positioned radially outward of the plurality of turbine blades.