DOWN WIND FLUID TURBINE
A shrouded fluid turbine includes a support structure, a nacelle body rotationally coupled to the support structure and configured to pivot about a pivot axis passing through the support structure, a rotor coupled to the nacelle body and having a rotor plane passing therethrough, the rotor plane being offset from the pivot axis, and an aerodynamically contoured turbine shroud surrounding the rotor and having a leading edge, a trailing edge and a plurality of mixing elements disposed therein. A center of pressure may be located downstream of the rotor plane with respect to direction of a fluid flow, and a combination of the nacelle body, the rotor, and the aerodynamically contoured turbine shroud may be configured to pivot about the pivot axis in response to a force exerted on the combination by the fluid flow such that the leading edge faces into the direction of the fluid flow.
1 . A shrouded fluid turbine comprising:
a nacelle body rotationally coupled to a support structure and being configured to pivot about a pivot axis passing through the support structure, at least a portion of the nacelle body being located upstream of the pivot axis with respect to a fluid flow direction;
a rotor coupled to the nacelle body and having a rotor plane passing therethrough, the rotor plane being offset downstream of the pivot axis with respect to the fluid flow direction; and
an aerodynamically contoured turbine shroud surrounding the rotor and having a leading edge, a trailing edge and a plurality of mixing elements disposed therein.
2 . The shrouded fluid turbine of claim 1 :
wherein a center of pressure is located downstream of the rotor plane, and
wherein a combination of the nacelle body, the rotor, and the aerodynamically contoured turbine shroud is configured to pivot about the pivot axis in response to a force exerted on the combination by the fluid flow such that the leading edge faces into the direction of the fluid flow.
3 . The shrouded fluid turbine of claim 2 , further comprising an aerodynamically contoured support structure shroud coupled at a first end with the nacelle body and at a second end with the leading edge of the aerodynamically contoured turbine shroud, the aerodynamically contoured support structure shroud being rotatable about the support structure.
4 . The shrouded fluid turbine of claim 3 , wherein the combination further includes the aerodynamically contoured support structure shroud.
5 . The shrouded fluid turbine of claim 2 , further comprising a radial member coupled at a first end with the nacelle body and at a second end with the trailing edge, the radial member having an aerodynamic shape.
6 . The shrouded fluid turbine of claim 5 , wherein the combination further includes the radial member.
7 . The shrouded fluid turbine of claim 2 , further comprising a radial member coupled at a first end with the nacelle body and at a second end with the inlet end, the radial member having an aerodynamic shape.
8 . The shrouded fluid turbine of claim 5 , wherein the combination further includes the radial member.
9 . The shrouded fluid turbine of claim 2 , further comprising an ejector shroud at least partially surrounding the trailing edge.
10 . The shrouded fluid turbine of claim 9 , wherein the combination further includes the ejector shroud.
11 . The shrouded fluid turbine of claim 1 , further comprising a passive yaw system.
12 . The shrouded fluid turbine of claim 1 , wherein the plurality of mixing elements are disposed along the trailing edge of the aerodynamically contoured turbine shroud.
13 . The shrouded fluid turbine of claim 1 , further comprising an aerodynamically contoured support structure shroud surrounding at least a portion of the support structure.
14 . A shrouded fluid turbine comprising:
a horizontal portion rotationally coupled to a yaw bearing and being configured to pivot about a pivot axis passing through a support structure;
a vertical portion coupled at a first end to the horizontal portion;
a nacelle body rotationally coupled to a second end of the vertical portion, at least a portion of the nacelle body being located upstream of the pivot axis with respect to a fluid flow direction;
a rotor coupled to the nacelle body and having a rotor plane passing therethrough, the rotor plane being offset downstream of the pivot axis with respect to the fluid flow direction; and
an aerodynamically contoured turbine shroud surrounding the rotor and having a leading edge and a trailing edge.
15 . The shrouded fluid turbine of claim 14 :
wherein a center of pressure is located downstream of the rotor plane, and
wherein a combination of the nacelle body, the rotor, and the aerodynamically contoured turbine shroud is configured to pivot about the pivot axis in response to a force exerted on the combination by the fluid flow such that the leading edge of the aerodynamically contoured turbine shroud faces into the direction of the fluid flow.
16 . The shrouded fluid turbine of claim 15 , further comprising an ejector shroud at least partially surrounding the trailing edge.
17 . The shrouded fluid turbine of claim 16 , wherein the combination further includes the ejector shroud.
18 . The shrouded fluid turbine of claim 17 , wherein the rotor, the aerodynamically contoured turbine shroud and the ejector shroud share a common central axis.
19 . The shrouded fluid turbine of claim 15 , further comprising a radial member coupled at a first end with the nacelle body and at a second end with the inlet end, the radial member having an aerodynamic shape.
20 . The shrouded fluid turbine of claim 19 , wherein the combination further includes the radial member.
21 . The shrouded fluid turbine of claim 14 , wherein the trailing edge further comprises a substantially linear segment having a substantially constant cross-section.
22 . The shrouded fluid turbine of claim 14 , further comprising a passive yaw system.