Ships – Hull or hull adjunct employing fluid dynamic forces to... – Having hydrofoil
Reexamination Certificate
2000-12-05
2001-07-03
Swinehart, Ed (Department: 3617)
Ships
Hull or hull adjunct employing fluid dynamic forces to...
Having hydrofoil
C114S242000, C114S245000
Reexamination Certificate
active
06253700
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to turbines and more particularly to turbines capable of unidirectional rotation under multidirectional fluid flows for use with hydro-pneumatic, hydro, wind, or wave power systems.
BACKGROUND OF THE INVENTION
A unidirectional turbine is a turbine capable of providing unidirectional rotation from bidirectional or reversible fluid flow, such as in tidal estuaries or from shifting wind directions. Generally, three basic types of unidirectional reaction turbines are known, the Wells turbine, the McCormick turbine, and the Darrieus turbine.
The Wells reaction turbine is a propeller-type turbine that comprises a series of rectangular airfoil-shaped blades arranged concentrically to extend from a rotatable shaft, as shown in FIG.
1
. Typically, the turbine is mounted within a channel that directs the fluid flow linearly along the axis of the rotatable shaft. The blades are mounted to extend radially from the rotatable shaft and rotate in a plane perpendicular to the direction of fluid flow. Regardless of the direction in which the fluid flows, the blades rotate in the direction of the leading edge of the airfoils, which, in
FIG. 1
, is counterclockwise.
The Wells turbine is capable of rapid rotation. The outer ends of its blades move substantially faster than the flowing air, causing high noise. Also, its efficiency is relatively low, because the effective surface area of the airfoil-shaped blades is limited to the outer tips, where the linear velocity is greatest. The blades cannot capture a substantial amount of the available energy in the fluid flowing closer to the shaft.
The McCormick turbine comprises a series of V-shaped rotor blades mounted concentrically between two series of stator blades, as shown in FIG.
2
. The rotor blades are mounted for rotation in a plane perpendicular to the direction of fluid flow. The stator blades direct fluid flow to the rotor blades. To achieve unidirectional rotation with bidirectional fluid flow, the outer stator blades are open to fluid flowing from one direction, while the inner stator blades are open to fluid flowing from the opposite direction.
The McCormick turbine is more quiet and could be more efficient than the Wells turbine. However, its rotational speed is too slow for direct operation of an electric generator. Its configuration is also complex and expensive to manufacture.
The Darrieus machine is a reaction turbine with straight airfoil-shaped blades oriented transversely to the fluid flow and parallel to the axis of rotation, as shown in FIG.
3
. The blades may be attached to the axis by circumferential end plates, struts, or by other known means. In some variations, the blades are curved to attach to the ends of the axis. A Darrieus reaction turbine having straight rectangular blades, mounted vertically or horizontally in a rectangular channel, has been placed directly in a flowing body of water to harness hydropower. The Darrieus turbine rotates with a strong pulsation due to accelerations of its blades passing through the higher pressure zones in the fluid that lowers the efficiency of the turbine.
Thus, a need still exists for a quiet, efficient, uniformly rotational, simple, unidirectional turbine that can operate at high speeds.
SUMMARY OF THE INVENTION
The present invention provides a unidirectional helical turbine capable of achieving high speeds needed for industrial electric generators. The turbine comprises a working wheel having a plurality of airfoil-shaped helical blades mounted transversely to the direction of fluid flow for rotation in a plane parallel to the direction of fluid flow. The blades extend between two supporting members, such as a pair of parallel discs, mounted on a rotatable shaft. The blades rotate in the direction of the leading edge of the airfoil, regardless of the direction of fluid flow.
The helical configuration ensures that a portion of the blades are always positioned optimally with respect to the fluid flow, thereby creating maximum thrust to spin the turbine. The continuous helical blades provide a continuous speed of rotation uninterrupted by accelerations and decelerations that accompany the Darrieus turbine as the blades pass the least and most efficient thrust zones. The skewed leading edges of the helical configuration further reduce resistance to the turbine rotation. The helical blades are operable with or without a channel to direct the fluid flow.
In a further embodiment, a cylindrical distributor is provided within the helical blades, to channel the fluid to the blades of the turbine, thereby increasing the fluid velocity near the blades and the power output of the helical turbine. The helical turbine combined with the cylindrical distributor attached to the turbine may also be used as an apparatus for lifting or lowering bodies such as submarines or submersible barges.
The helical turbine may also be provided with multiple layers or rings of concentrically arranged helical blades. The blades of adjacent rings are shifted circumferentially such that they do not overlap each other in the fluid flow. That is, the inner blades are positioned within the spaces between the outer blades. The multilayer arrangement increases the torque and power output.
In a case when the helical turbine is used with a hydro-pneumatic energy converter, a channel interconnects a pair of chambers in which air is alternately compressed and expanded due to the alternate filling and emptying of the chambers with water. The alternate compression and expansion causes the air flow to alternate in direction through the connecting channel. The helical turbine, mounted in the channel, is in this manner able to capture the energy in the flowing air and convert it to rotary mechanical energy. The turbine is connected to an electric generator for generation of electrical energy. No additional gearing speed increaser is usually required, since the turbine rotates fast enough for conventional generators.
In a hydro application, the helical turbine may be mounted in a vessel located in a current of about 5 feet per second or greater, such as in a tidal channel. The turbine is located below the surface of the water, where the current velocity is greatest, and is retained in that location by virtue of the vessel's rise and fall with the water. The helical turbine embodiment is particularly suited to this application. A housing to channel the flow to the turbine may by provided if desired, but is not necessary if the current velocity is sufficiently great. The turbine is connected to a suitable electric generator, which may be mounted on the vessel in a water tight chamber. The turbine can also be used in conventional applications, such as in dams.
The helical turbine is also efficiently configured in a modular form comprising, preferably, two or more helical blades in spirals extending from one end to the other. For wind power applications, a plurality of modules is arrayed, vertically or horizontally, on rotatable shafts which are supported by lightweight structures anchored to the ground by guy wires. The optimally designed modules provide unidirectional and uniform, non-oscillating rotation in any non-zero angle between the turbine shaft and wind direction.
The helical turbine is also useful to provide propulsion or supplement engine-driven propulsion of a marine vessel utilizing the power of ocean waves. The helical turbine is operable under the multidirectional oscillations of ocean waves and can develop a substantial axial torque useful in the propulsion of marine vessels.
REFERENCES:
patent: 707857 (1902-08-01), Marburg
Northeastern University
Swinehart Ed
Weingarten, Schurgin Gagnebin & Hayes LLP
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