Patent Application
20100135806
1. Technical Field
The subject matter described here generally relates to wind turbines, and, more particularly, to wind turbine blades with hinged tips.
2. Related Art
A wind turbine is a machine for converting the linetic energy in wind into mechanical energy. If the mechanical energy is used directly by the machinery, such as to pump water or to grind wheat, then the wind turbine may be referred to as a windmill. Similarly, if the mechanical energy is converted to electricity, then the machine may also be refelled to as a wind generator or wind power plant.
Wind turbines are typically categorized according to the vertical or horizontal axis about which the blades rotate. One so-called horizontal-axis wind generator is schematically illustrated in
The blades 10 generate lift and capture momentum from moving air that is them imparted to the rotor as the blades spin in the “rotor plane.” Each blade 10 is typically secured to the hub 9 at its “root” end, and then “spans” radially “outboard” to a free, “tip” end. The front, or “leading edge,” of the blade 10 connects the forward-most points of the blade that first contact the air. The rear, or “trailing edge,” of the blade 10 is where airflow that has been separated by the leading edge rejoins after passing over the suction and pressure surfaces of the blade. A “chord fine” connects the leading and trailing edges of the blade in the direction of the typical airflow across the blade. The length of the chord line is simply the “chord.” The thickness of a blade 10 varies across the span, and the term “thickness” is typically used to describe the maximum distance between the low pressure suction surface and the high pressure surface on the opposite side of the blade for any particular chord line. The outboard ends of the blades 10 are called “tips” and the distance from the tip to the root, at the opposite end of the blade, is called the “span.” The shape of the blade 10, when viewed perpendicular to the direction of flow, is called the “planform.”
World Intellectual Property Organization Publication No. 2006/133715 discloses a blade for a wind turbine power plant including at least one joint transversally to the longitudinal direction of the blade, about which the outermost part of the turning of the blade out of the original face of rotation of the blade can be controlled by an actuator whereby the rotor area can be controlled in operation. The joint may be turned about a rotary joint such as a hinge or configured as a resilient joint. Several joints may be located in succession in the blade.
Various drawbacks associated with such conventional approaches are addressed here in by providing, in various embodiments, a wind turbine blade including a plurality fins, each fin rotatably-joined to a tip of the blade
Various aspects of this technology will now be described with reference to the following figures (“FIGS.”) which are not necessarily drawn to scale, but use the same reference numerals to designate corresponding parts throughout each of the several views.
The blade tip 20 includes one or more fins 22 which are each secured to the blade by a joint 24. For example, as shown in
The fins 22 may be have an aerodynamic shape. For example, as illustrated in the end views of
The joint(s) 24 provide rotational degrees of freedom in one or more axes for the corresponding fin 22. For example, as illustrated in
One or more actuators 32 may be configured, for example with a positional motor, to rotate the fins 22 relative to the ball joints 24 in various configurations. For example,
The technology disclosed here offers various advantages over conventional approaches for enhancing the performance of wind turbine blades through reduced thrust, noise and vibration, and increased torque. For example, the fins 22 may be controlled so that the blades 20 provide increased power in response to higher demand for that power. Conversely, reductions in power production may also be obtained using the actuator 32 and/or pitching the blades. The actuator 32 can be also used increase blade performance by reducing the tip vortex intensity, and thus providing lower thrust, lower drag, less noise, less vibration. The fins 32 can also be arranged to minimize the distance between the blade tips 20 and the tower 4 (
It should be emphasized that the embodiments described above, and particularly any “preferred” embodiments, are merely examples of various implementations that have been set forth here to provide a clear understanding of various aspects of this technology. One of ordinary skill will be able to alter many of these embodiments without substantially departing from scope of protection defined solely by the proper construction of the following claims.
