Lightweight composite truss wind turbine blade
A lightweight wind turbine blade formed with a truss support structure assembly of composite truss joints including composite spar and cross members attached to and supporting in spaced relation a spine of lightweight rib panels. The rib panels are oriented in parallel spaced relation from one another and individually molded with perimeters defining individual areas of curvature for the finished blade assembly. The truss support structure is covered with a lightweight fiberglass or hardened fabric skin attached to and fitted on respective rib panel edges forming an airfoil structure.
1. A method for operating a wind turbine, comprising:
carrying multiple wind turbine blades with a spindle,
transmitting loads from at least one of the wind turbine blades to the spindle via a truss structure that includes a wind turbine blade skin, a plurality of spaced-apart wind turbine blade rib panels positioned within the skin, multiple spars connected to and extending between neighboring rib panels in a spanwise direction, and multiple cross members extending diagonally between neighboring spars; and
subjecting the wind turbine blades to cyclically varying gravitational loads by rotating the spindle about a generally horizontal axis.
2. The method of claim 1 , further comprising changing a pitch angle of the wind turbine blades relative to the spanwise direction.
3. The method of claim 1 wherein subjecting the wind turbine blades to cyclically varying gravitational loads includes subjecting the wind turbine blades to cyclically varying loads in a generally chordwise direction.
4. The method of claim 1 wherein the truss structure includes a first spar positioned toward a leading edge of the at least one blade and a second spar positioned aft of the first spar toward a trailing edge of the at least one blade, and wherein transmitting loads includes transmitting loads via a plurality of cross members extending diagonally between the first and second spars.
5. The method of claim 1 wherein the wind turbine blade skin includes a low pressure surface facing in a first direction and a high pressure surface facing in a second direction opposite the first direction, and wherein transmitting loads includes transmitting loads with cross members extending diagonally between neighboring spars, proximate to the high pressure surface.
6. The method of claim 1 wherein the wind turbine blade skin includes a low pressure surface facing in a first direction and a high pressure surface facing in a second direction opposite the first direction, and wherein transmitting loads includes transmitting loads with cross members extending diagonally between neighboring spars, proximate to the low pressure surface.
7. The method of claim 1 , further comprising carrying the spindle with a fixed wind turbine tower.
8. The method of claim 1 wherein individual rib panels have a broad airfoil-shaped surface facing in the spanwise direction.
9. The method of claim 1 wherein individual rib panels have an outer perimeter edge and are connected to the spars at the outer perimeter edge.
10. A wind turbine blade assembly, comprising:
a plurality of wind turbine blades, with at least one of the blades having:
a wind turbine blade skin;
a plurality of wind turbine blade rib panels positioned within the skin;
a plurality of spars extending between neighboring rib panels in a spanwise direction; and
a plurality of cross members extending diagonally between the spars, with the rib panels, spars and cross members forming a truss structure; and
a horizontal spindle carrying the wind turbine blades for rotation about a horizontal axis.
11. The assembly of claim 10 wherein at least one of the spars has a first portion connected to a second portion at a spar joint.
12. The assembly of claim 10 , further comprising a hub carried by the spindle, and wherein at least one of the blades further comprises:
a generally circular mounting ring;
a transition structure connected between the truss structure and the mounting ring, wherein the spars are attached to the transition structure; and
a plurality of connectors connecting the mounting ring to the hub.
13. The assembly of claim 10 , further comprising a continuous load bearing member extending diagonally and spanwise in a zig-zag manner between neighboring spars.
14. The assembly of claim 13 wherein the continuous load bearing member is one of the cross members.
15. The assembly of claim 10 , further comprising:
a fixed tower carrying the spindle and the plurality of wind turbine blades;
a hub carried by the spindle, and wherein each of the plurality of wind turbine blades includes:
a wind turbine blade skin;
a plurality of wind turbine blade rib panels positioned within the skin;
a plurality of spars extending between neighboring rib panels in a spanwise direction;
a plurality of cross members extending diagonally between the spars, with the rib panels, spars and cross members forming a truss structure;
a circular mounting ring;
a transition structure connected between the truss structure and the mounting ring, wherein the spars are attached to the transition structure; and
a plurality of connectors connecting the mounting ring to the hub.
16. The assembly of claim 15 wherein the truss structure includes a first spar positioned toward a leading edge of the at least one blade, a second spar positioned aft of the first spar toward a trailing edge of the at least one blade, and a plurality of cross members extending diagonally between the first and second spars.
17. The assembly of claim 15 wherein the wind turbine blade skin of the at least one blade includes a low pressure surface facing in a first direction, a high pressure surface facing in a second direction opposite the first direction, and cross members extending diagonally between neighboring spars, proximate to the high pressure surface.
18. The assembly of claim 15 wherein the wind turbine blade skin of the at least one blade includes a low pressure surface facing in a first direction, a high pressure surface facing in a second direction opposite the first direction, and cross members extending diagonally between neighboring spars, proximate to the low pressure surface.
19. The assembly of claim 10 wherein individual rib panels have a broad airfoil-shaped surface facing in the spanwise direction.
20. The assembly of claim 10 wherein individual rib panels have an outer perimeter edge and are connected to the spars at the outer perimeter edge.
21. A wind turbine blade assembly, comprising:
a fixed tower;
a spindle rotatably carried by the tower;
a hub carried by the spindle; and
a plurality of wind turbine blades connected to the hub, wherein each wind turbine blade includes:
a wind turbine blade skin;
a plurality of wind turbine blade ribs positioned within the skin;
a plurality of spars extending between neighboring ribs in a spanwise direction;
a plurality of cross members extending diagonally between the spars, with the ribs, spars and cross members forming a truss structure;
a circular mounting ring;
a transition structure connected between the truss structure and the mounting ring, wherein the spars are attached to the transition structure; and
a plurality of connectors connecting the mounting ring to the hub.
22. The assembly of claim 21 wherein for each wind turbine blade:
the wind turbine blade skin has a leading edge and a trailing edge;
a first spar is positioned toward the leading edge;
a second spar is positioned toward the trailing edge; and
at least a portion of the cross members extend diagonally between the first and second spars.