Abstract: Example embodiments are directed to fluid turbines that include a turbine shroud, a rotor and an ejector shroud. The turbine shroud includes an inlet, an outlet, a leading edge and a trialing edge. The leading edge of the turbine shroud can be round and the trialing edge of the turbine shroud can include linear faceted segments. The rotor can be disposed within the turbine shroud and can define a rotor plane. The turbine shroud can provide a first portion of a fluid stream to the rotor plane via the inlet of the turbine shroud. The ejector shroud can provide a second portion of the fluid stream to the outlet of the turbine shroud via an open area. An example method of operating a fluid turbine is also provided.

Abstract: A shrouded wind turbine comprises a shroud disposed about an impeller. The impeller surrounds a nacelle body which is shaped to enhance smooth flow of wind through the impeller. Some embodiments include an inlet and an outlet in the nacelle body, allowing airflow through an interior cavity. Other nacelle bodies may be tapered, flared, include mixing lobes around a trailing edge, or may have other shapes that enhance fluid flow. Some nacelle bodies include an annular groove that promotes flow attachment. Maintaining airflow attachment to the nacelle body within the turbine increases the energy generation capacity of the wind turbine.

Abstract: One or more variable pitch airfoils in fluid communication with a rotor of a fluid turbine can control the amount of energy directed to the rotor, and further control the amount of energy generated by the turbine. Varying the pitch of the airfoils may provide a means of controlling the power output of a fluid turbine without the need to control the pitch of the rotor blades, and may further provide a means of mitigating the effects of wind shear on the rotor. Variable pitch airfoils may also include a means of controlling the active power, reactive power and SCADA, of a group of fluid turbines.

Abstract: A fluid turbine comprises a turbine shroud, an ejector shroud, and a means for extracting energy from a fluid stream. The means for extracting energy is located in the annulus between the turbine shroud and the ejector shroud. High-energy fluid can flow through the turbine shroud to bypass the means for extracting energy. Energy is extracted from the fluid passing through the means to form a low-energy fluid stream. The high-energy fluid and the low-energy fluid can then be mixed. The turbine shroud and/or the ejector shroud has mixing lobes to increase the mixing of the two fluid streams.

Abstract: Disclosed are wind turbines comprising a turbine shroud and optionally an ejector shroud. The shrouds are segmented, or in other words have longitudinal spaces between segments. Such wind turbines have reduced drag load, particularly those loads due to off-axis wind forces.

Abstract: 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.

Abstract: Example embodiments are directed to shrouded fluid turbines that include a turbine shroud and a rotor. The turbine shroud includes a an inlet, an outlet and a plurality of mixer lobes circumferentially spaced about the outlet. The rotor can be disposed within the turbine shroud and downstream of the inlet. The rotor includes a hub and at least one rotor blade engaged with the hub. The shrouded fluid turbines further include a passive yaw system for regulating a yaw of the shrouded fluid turbine. The shrouded fluid turbine defines a center of gravity and a center of pressure. The center of gravity can be offset from the center of pressure. Example embodiments are also directed to methods of yawing a shrouded fluid turbine.

Abstract: Example embodiments are directed to shrouded fluid turbines that include a turbine shroud and a rotor. The turbine shroud includes a plurality of mixer elements and the rotor can be disposed within the turbine shroud. The shrouded fluid turbine further includes a hybrid yaw system having a passive yaw system and an active yaw system for regulating a yaw of the shrouded fluid turbine. The hybrid yaw system further includes a torque limiter. Example embodiments are also directed to methods of yawing a shrouded fluid turbine. Example embodiments are further directed to hybrid yaw systems for a shrouded fluid turbine that includes a shrouded fluid turbine assembly rotationally engaged with a tower. The hybrid yaw system includes a passive yaw system and an active yaw system associated with the shrouded fluid turbine.

Abstract: A shrouded fluid turbine includes a ringed airfoil having a leading edge, a trailing edge, an outer surface, an inner surface, and a body extending from the leading edge to the trailing edge. The shrouded turbine further includes a rotor surrounded by the ringed airfoil. The rotor is disposed downstream of the leading edge and about a central axis of the fluid turbine. The shrouded turbine further includes an aperture extending through the body of the ringed airfoil between the outer surface and the inner surface. The aperture is configured to mix a first fluid flow adjacent to the outer surface of the ringed airfoil and a second fluid flow downstream of the rotor.

Abstract: The present disclosure relates to fluid turbines having a turbine shroud assembly formed with mixing elements (e.g., both inwardly and outwardly curving elements) having airfoil cross sections. These airfoils form ringed airfoil shapes that provide a means of controlling the flow of fluid over the rotor assembly or over portions of the rotor assembly. The fluid dynamic performance of the ringed airfoils directly affects the performance of the turbine rotor assembly. The mass and surface area of the shrouds result in load forces on support structures. By delaying or eliminating the separation of the boundary layer over the ringed airfoils, boundary layer energizing members (e.g., vortex generators, flow control ports) on the ringed airfoils increase the power output of the fluid turbine system and allow for relatively shorter chord-length airfoil cross sections and therefore reduced mass and surface area of the shroud assemblies.

Abstract: A ring airfoil with a voluminous leading edge region, an intermediate region, a trailing edge region including a flap. The ringed structural leading edge region combined with a rigid trailing edge region having intermediate discrete support portions extending therebetween provides sufficient rigidity to support the flap on the trailing edge region while using a membrane intermediate surface to form a portion of the intermediate region of the airfoil.

Abstract: Systems for protecting a wind turbine in high wind conditions are disclosed. A shrouded turbine may have an ejector shroud disposed adjacent and downstream of a turbine shroud. In one version, the ejector shroud can move to surround the turbine shroud. In another version, the turbine can be pivoted on a support tower to cover the intake end of the turbine and rotate the turbine about an axis at a right angle to the tower axis. In another version, the turbine is supported by a telescoping tower which may be retracted to lower the turbine in high winds. In another version, the tower sections may be connected by a pivotable connection and supported by guy wire(s) which may be lengthened to lower the upper tower section pivotally.

Abstract: A shrouded wind turbine includes a shroud with an exterior surface that includes a smooth outer surface. The smooth outer surface is large enough that additional devices, particularly advertising displays or solar panels, can be mounted to the shroud to more efficiently use available surface area, both on the wind turbine itself and on the footprint of the wind turbine.

Abstract: Shrouded fluid turbines having features for setting, adjusting or controlling a blade tip-shroud clearance are described. Also described are methods for setting, adjusting or controlling a blade tip-shroud clearance in a shrouded fluid turbine.

Abstract: A fluid turbine lightning protection system includes at least one air termination device, formed at least in part of an electrically conductive material, that can be positioned on a shroud of a fluid turbine and placed in electrical communication with a down conduction system. The down conduction system is in electrical communication with an earth-termination system configured to dissipate electricity transferred thereto to the ground. The at least one air termination device is configured to intercept a lightning strike and direct it through the down conduction system, the earth-termination system, and into the ground. The at least one air termination device may be positioned on a turbine shroud based on a “Rolling Sphere” derivation wherein the “Rolling Sphere” derivation is derived from the equation r=10·I0.65, where I is the peak current in kiloamperes and r is the rolling sphere radius in meters.

Abstract: A mixer-ejector wind turbine uses an ultracapacitor system to store power from the variable generation of power by a permanent magnet generator. The system takes advantage of the MEWT area ratio, the higher velocity at the outer radius of the turbine, and the ability of the ultracapacitor system to store almost all of the input charge.

Abstract: A ring fluid foil including a modified trailing portion for a shrouded fluid turbine and shrouded fluid turbine including such ring fluid foils are described herein. The modification of the trailing portion increases flow turning by the fluid foil without, or with reduced, boundary layer separation on a suction side of the fluid foil.

Abstract: A wind turbine has an impeller surrounded by a turbine shroud and/or an ejector shroud, wherein the turbine shroud and/or the ejector shroud include inflatable portions and/or flexible inflatable portions. In some embodiments, the turbine shroud and/or the ejector shroud include internal rib members whose shape or length can be changed to alter the characteristics of the wind turbine.

Abstract: Turbine systems for extracting energy from water traveling relative to the turbine system can include a rotor assembly for extracting the energy, a turbine shroud having a turbine shroud inner volume within which at least a portion of the rotor assembly is disposed, and an ejector shroud disposed adjacent to the turbine shroud. The turbine shroud and the ejector shroud can each have a terminus comprising a plurality of turbine shroud mixer elements or ejector shroud mixer elements, respectively. One or more of the mixer elements and ejector shrouds comprise a mixer/ejector pump which increases the energy extraction potential of the turbine system. One or more of the turbine shroud mixer elements, ejector shroud mixer elements, and ejector shroud and turbine shroud inlets can be asymmetric along a plane passing through the axis of rotation of the rotor assembly.