Abstract:
The windmill assembly is a low drag, streamlined body of revolution that captures the kinetic energy content of the accelerated laminar air surrounding the body. The assembly includes a power-generating, wind-driven turbine that is compact, lightweight and capable of producing a substantially greater output than a conventional windmill with a comparable size rotor. The turbine includes a protruding aerodynamic nose and outer cowling that provide a streamlined, wind-collecting inlet section that constricts the incoming air stream and increases its velocity through the turbine blades. The turbine further includes an exit section designed to exhaust the air stream with a minimum of turbulence. One or more generators are coupled to a turbine wheel, and are electrically switched on and off to maximize the energy capture over the full range of ambient winds. The wind turbine assembly may be configured around a blimp-type body having counter-rotating turbine assemblies.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a new wind driven turbine with improved efficiency to generate electric power, and in particular to a turbine design that augments the fluid stream towards the blades of the turbine. The present invention relates broadly to apparatus for increasing the flow speed of a fluid medium such as air or water and for recovering its kinetic energy. This invention further relates to the harnessing of wind power for converting kinetic wind energy to mechanical and/or electrical power. The present invention is described with reference to wind as the medium; however, those of ordinary skill in the art will appreciate that the invention is applicable to other fluid mediums (e.g., gases and liquids), such as steam and water. 
     Because energy from the wind is free and non-polluting, much affention has been given to improving the efficiency and lowering the cost of windmill structures. Energy has been extracted from moving air for thousands of years using hundreds of different designs from the simplest sails that push ships to sophisticated computer controlled windmills that generate electricity. After many hundreds of years of refinement, the basic three bladed (propeller type) windmill design using computer controlled variable pitch airfoils has become the dominant means for generating electricity. All of these different solutions take advantage of the principle that the faster the relative wind, then the more energy that can be extracted. An efficient three bladed windmill extracts about one-half of the kinetic energy in the wind to spin the blades. However, there are some limitations with that conventional design approach. For example, the speeding blade tips can shed vortices and create swirl wakes that steal energy while the shaft end of the blade next to the center hub hardly moves. Using twisted (variable pitch) blades help accommodate the rotational speed difference between the hub and the blade tip, but it cannot perform with optimal output for the full dynamic range of the fluctuating winds. 
     It is well known that the recoverable kinetic energy is proportional to the third power of the wind velocity or speed. Thus, doubling the air speed will increase the power recovered by eight times. However, there are generally acknowledged minimum wind speeds that will result in recoverable energy. It is generally acknowledged that a wind speed of five meters per second or about eleven miles per hour is required in order to make energy recovery economically feasible. In many areas of the world, the predominant wind speed is at or only slightly above the level required for economical energy recovery and, therefore, wind energy has not been harnessed effectively. It is important to note that the total kilowatt hours produced over a period of time with a wide range of wind velocities is more important than how many kilowatt-hours the windmill can produce at its maximum design speed. How much power it produces when the prevailing wind is just a breeze or when it is the strongest of winds are important factors in the total equation. 
     The amount of power that a conventional propeller windmill can generate is directly proportional to the square of the diameter of the circle of rotation of the propeller tips, as well as the cube of the wind velocity. It is also known that the further from the axis of rotation the wind force can be applied, the greater the generated torque or rotational force. Further, increasing the diameter of the propeller decreases the rotational speed of the windmill. The longer blades are more difficult and costly to make so they must be light in weight, properly shaped and capable of responding to the prevailing wind without undergoing excessive deflection, distortion or failure. 
     Some horizontal axis windmill designs investigated incorporate a funnel that employs the Principle of Continuity that states that the product of the velocity and the cross sectional of an air-stream area remains constant. Accordingly, the velocity in an air stream must increase when passing through such constrictions. For example, if the exit area in a funnel were one-half of the entrance opening, then the air would have to exit at double the intake velocity, providing a so-called Venturi effect. However, such known designs have the disadvantage that most of the oncoming air does not enter the funnel but would flow around the outside due to backpressure. Further, the small amount of air that does pass through the funnel would be directed at the central area around the hub of the windmill where it would be least effective in generating power. Others claim a more efficient design using the Venturi principle by proportioning an exterior truncated cone or collector fin to capture more of the air and by adding an inverted cone or stream liner in the center of the cone to divert the air out and around a central generator and into a series of turbine blades. The following patents are related to windmills and turbines, the contents of each are hereby incorporated herein by reference: U.S. Pat. Nos. 4,140,433; 4,320,304; 4,411,588; 5,457,346; 6,382,904. 
     Basically, Venturi based windmill inventions first capture some wind, and then try to squeeze and accelerate it through one or more cone shapes in front of the turbine blades. No prior known wind turbine systems have utilized the approach of first accelerating the wind in a laminar flow around a streamlined body before it captures the accelerated air and sends it through the circumferentially mounted turbine blades. The accelerated “laminar air” that flows over an aircraft wing to help lift it up into the sky contains the same kinetic energy stream used by the turbine of the present invention to generate electricity. 
     There is a need in the windmill and turbine art for a wind driven power generator that is capable of generating substantially more power than equal diameter conventional propeller windmills. There is a further need for a wind driven power generator that is compact in size, including several discrete subassemblies that can be made with a modular construction, and is adapted to incorporate and drive an electrical power generator and/or an apparatus for driving an external electrical power generator or other device. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to devices that accelerate the air stream before it is captured and directed toward the turbine blades to extract energy and generate power. Similarly, efficient water turbines do not “just take the fluid as it comes” out of the end of a hose to turn a turbine and generate electricity. They first accelerate the water stream through a nozzle before it blasts the turbine blades. The present invention does not just “take the wind as it comes.” The present invention provides a novel system to accelerate the wind before it blasts the turbine wheel blades to generated electricity. It is a novel wind power generator in the form of a relatively low cost turbine that includes a rotor and apparatus for directing the airflow to maximize the rotational force applied to the rotor blades. The wind driven turbine of the present invention further provides a modular construction that permits it to be assembled quickly by semiskilled workers without need for costly and sophisticated equipment, and provides a high power-to-weight ratio at relatively low cost and without sacrifice of structural integrity. 
     Since wind generated power increases with the cube of the relative air velocity, doubling the actuator speed theoretically increases the power available by eight fold. With some important and unique differences, the process is similar to an efficient gas or water turbine in which the fluid is accelerated through a nozzle before it blasts the turbine blades to generate power. First, the present invention accelerates the wind around a streamlined nose, then captures the accelerated air in the laminar flow close to a streamlined body and passes it through ducted perimeter turbine wheel blades for maximum torque. Whereas prior known Venturi based windmills first capture some wind, then attempt to squeeze and accelerate it through one or more cone shapes toward the center hub area of the turbine wheel, the present invention takes the unique approach of first accelerating the wind in a laminar flow around a stream lined body before it captures the accelerated air and sends it through the circumferentially mounted turbine blades. The exact shape of the nose, vanes, blades and tail depend on the specific requirements of size, design wind speeds, environmental conditions, etc. However, distinguishing features of the turbine of the present invention include the nose and tail that each extend outward beyond the cowlings of the turbine housing. 
     This invention relates to devices and methods for improving the efficiency of wind driven turbines to generate electric power, and, in particular, to a turbine design that augments the air stream directed towards the blades of the turbine. The present invention relates broadly to apparatus for increasing the flow speed of a medium such as air or water and for recovering its kinetic energy. The invention is described below with reference to wind as the medium, but it will be appreciated that the invention with modifications that are well known to those of ordinary skill in the art is applicable also to a medium such as water. The present power-generating wind-driven turbine offers the advantage that it is compact and lightweight and is capable of producing a substantially greater output than a conventional windmill with a comparable size rotor. The laminar air turbine is configured with an aerodynamic nose in front of a cowling and fixed vanes. The nose and cowling form a streamlined wind-collecting duct designed to turn and accelerate the air stream into the turbine blades. The turbine wheel duct is configured with an array of curved energy capturing blades and an exit section designed to exhaust the air stream into the tail section and beyond with a minimum of turbulence. The present tail assembly is configured to turn the exit air inward toward the tail. Unlike heretofore known windmills, the tail section of the windmill of the present invention includes a series of perimeter vanes inside a duct fixed to the stationary tail to turn the slower exit air parallel to the wind and inward along the tapered tail to follow the wind and eliminate energy stealing swirls. 
     The windmill of the present invention may be configured as a simpler, but less efficient, configuration in which the nose and tail vanes are deleted and the turbine blades become a series of curved pinwheel blades or airfoils on the wheel between the nose and tail sections. Alternatively, the windmill of the present invention may include two counter-rotating turbine wheels to the basic windmill described herein in which the exit ducted air stream from a first turbine wheel enters ducted blades of a second turbine wheel to turn it in the opposite direction. The total energy captured is expected to be about the same as the single turbine wheel version; however, each wheel would be rotating slower and their opposing precessions would cancel out. Their counter rotation speeds may be equalized by blade configurations and/or with a stationary equalizing gear or friction wheel. Alternatively, the power may be captured using the differential speeds of the counter-rotating turbine wheels by making one wheel the generator stator and the other the rotor. 
     A further variation of the windmill assembly of the present invention configured for very large air turbines includes providing two adjacent belts of counter-rotating turbine rings around a custom shaped, tethered “blimp.” The blimp could be floated or flown up to the optimum elevation for power generation and then retracted into a protective shed during high winds or stormy weather or for periodic maintenance. 
     Unlike the nosecones of typical propeller bladed windmills that are shaped to reduce the hub wind-drag and protect the generator, the nose of the present invention is specially shaped to accelerate the wind around the nose as a thin laminar layer of fast moving air into the perimeter turbine blades. Unlike typical windmills whose blades spin the supporting shaft to transfer power, the turbine wheel in this invention spins freely on a stationary backbone axle. Unlike typical propeller windmills, the blades and vanes of the present invention are enclosed in a duct to prevent energy losses due to vortex shedding and trailing swirls. 
     Unlike typical two or more bladed windmills in which a significant percent of the winds force is exerted in the central area where it produces minimal torque, the nose of the present invention directs and accelerates the wind away from the central area into a perimeter array of turbine blades inside a cowling enclosed duct to develop maximum torque. Unlike a typical water or gas turbine whose nozzles jet a stream tangentially at the rotor blades at one or two points of the turbine wheel, the accelerated air in this invention is directed at all of the turbine blades around the perimeter simultaneously. 
     Unlike the Venturi based windmills, and all other known vertical or horizontal axis windmills that use blades that deflect the wind significantly less than ninety degrees; the present invention turbine blades turn the wind significantly more than ninety degrees for optimum power output. Unlike propeller bladed windmills, Venturi based windmills, and all other known windmills, the present invention provides for the use of several perimeter mounted electric generators that can be sequentially turned on or off in response to varied winds to safely hold the turbines and generators speed at their highest levels of power production. Unlike any other known windmill, the present invention has counter-rotating belts of turbine wheels that are light and stable enough to be wrapped around large blimp like bodies and that use the laminar air principle to efficiently generate large quantities of electric power in the fast and stable winds at higher elevations. 
     The laminar air turbine of the present invention is unlike all other known windmills. 
     Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment the turbine assembly of the present invention. 
         FIG. 2  is a side plan view of one embodiment of the turbine assembly of the present invention. 
         FIG. 3  is a side plan view in partial cross-section of one embodiment of the nose of the turbine body. 
         FIG. 4  is a front plan view of one embodiment of the entry vanes of the turbine body nose. 
         FIG. 5  is a side plan view in partial cross-section of one embodiment of the turbine wheel of the turbine assembly of the present invention. 
         FIG. 6  is a front plan view of one embodiment of the turbine blades of the turbine wheel assembly of the present invention. 
         FIG. 7  is a side plan view in partial cross-section of one embodiment of the wheel assembly with the turbine blades exposed for viewing of the present invention. 
         FIG. 8  is a schematic diagram depicting the airflow through the fixed vanes and the rotating turbine blades of the present invention. 
         FIG. 9  is a side plan view in partial cross-section of one embodiment of the tail assembly of the present invention. 
         FIG. 10  is a rear plan view of one embodiment of the exit vanes of the tail of the present invention. 
         FIG. 11  is a perspective view of one embodiment the turbine assembly of the present invention configured as a blimp. 
         FIG. 12  is a perspective view of one embodiment the turbine assembly of the present invention configured as a blimp positioned within a turntable-based shed. 
         FIG. 13  is a side plan view of one embodiment of an electric generator station of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a minimum drag, streamlined body-of-revolution having a rounded nose and tapered tail halves that are separated for the insertion of one or more rows of turbine wheels. The present invention inserts one or more rows of ducted turbine wheels between the low-drag nose and tail halves to capture that accelerated laminar wind close to the body and to send that accelerated wind through the turbine blades to generate electricity. In principle, the less a wind stream is disturbed as it passes a stationary body the lower its wind drag force will be. A streamlined body-of-revolution achieves the lowest drag by separating the wind at the rounded nose, causing it to accelerate around the body in a smooth laminar fashion so as to merge at the tail with the surrounding wind, with minimum induced turbulence. The subject windmill can be described as a low drag, streamlined body in which the accelerated laminar air surrounding the body is captured for its energy content. 
     Referring now to the drawings for purposes of illustration and particularly to  FIGS. 1 and 2 , the turbine assembly  30  of the present invention includes a nose assembly  40 , a turbine wheel assembly  60  and a tail assembly  80 . The turbine assembly includes an electric generator  102 , with a removable base  110  and a method of transferring power  100 . 
     The nose assembly  40  includes a pipe or tubular backbone  46 , a disk bulkhead  52 , and a nose gusset  44 . The aerodynamic nose includes a set of circumferentially spaced fixed vanes  50  and a nose cowling  48 . The nose assembly is fixed to the pipe backbone, and may house one or more generators  102 . The turbine wheel assembly  60  includes a turbine hub  62 , a disk bulkhead  72 , an inner band  74 , a set of circumferentially spaced fixed blades  70 , and an outer cowling  68 . The turbine wheel  60  is free to spin on the axle fixed to first pipe backbone  46 . The wheel assembly is supported by the disk bulkhead. The tail assembly  80  includes a pipe backbone  86 , a disk bulkhead  92  and a tail gusset  84 . The aerodynamic tail assembly includes a set of circumferentially spaced fixed vanes  90  and a tail cowling  88 . 
     As shown in  FIG. 2 , the nose cowling  48  surrounding the aft end of the aerodynamic nose  40  is configured to accelerate and direct the airflow through the plurality of fixed vanes  50  in alignment with the corresponding turbine wheel components. The turbine wheel assembly  60  includes an outer band  68  and blades  70 , configured to capture some of the energy in the high velocity air by turning the turbine wheel and then passing the air into the tail assembly  80 . The tail assembly, vanes and cowling are in alignment with the corresponding components of the turbine wheel to direct the air out along the aerodynamic tail  82 . 
     Referring again to  FIG. 2 , an altemative embodiment of the turbine assembly  30  includes a power takeoff wheel  100  and associated generator  102  configured as part of the nose assembly  40 . In such an embodiment, the nose assembly includes a pipe backbone  46  embedded within the aerodynamic nose. The pipe backbone of the nose assembly is configured to mate with or otherwise secure to an axle  66  within the turbine wheel assembly  60 . Similarly, the tail assembly  80  includes a pipe backbone  86  configured to mate with or otherwise secure to the axle of the turbine wheel assembly. One or more power takeoff wheels and generator assemblies may be configured within the nose assembly, may be configured as part of the tail assembly or be included within the section that contains the support column  110 . Those of ordinary skill in the art will appreciate that various forms of the power takeoff wheel and generator assembly may be implemented within the scope of the present invention. 
     Referring now to  FIGS. 3 and 4 , the nose assembly  40  is configured with an aerodynamic nose  42 . Incoming airflow is directed across the face of the nose, through an inlet  43  and into the nose cowling  48 . The nose cowing may be configured to be relatively straight (flat) and parallel to the pipe backbone  46  or may be configured to flare outward toward the nose. The accelerated laminar air entering the nose cowling is directed to a series of fixed vanes that are curved in a manner for optimum energy transfer of the wind kinetic energy to the turbine blades. The exit air from the vanes  50  and the nose cowling is then directed through an outlet  53  to the blades  70  of the turbine wheel assembly  60 . The inner end  49  of the nose pipe assembly is configured to mate with and secured to the axle  66  ( FIG. 5 ). All of the components with the exceptions of the electric generator  102  and power takeoff wheel  100  are securely joined together by various devices familiar to those with ordinary skill in the art. There are many methods for transferring torque from the turbine wheel to the generator. The direct friction drive wheel  100  rolling over the inner surface of  74  is one illustrated example. By using a series of two or more perimeter mounted generators that can be sequentially switched on and off in response to ambient winds, the turbine and generator speeds can be brought to and maintained at their optimum levels of power output over the full range of wind speeds. 
     Referring now to  FIGS. 5 and 6 , the turbine wheel assembly  60  includes a plurality of curved blades  70  that are configured to extract the kinetic energy of the accelerated air exiting from the nose vanes, and convert it into rotational power in the turbine wheel assembly. The turbine assembly is further configured with air inlets  63 , a disk bulkhead  72  that surrounds the center portion of the stationary axle  66  and an inner band  74  that is supported by the bulkhead. The turbine hub  62  is provided with suitable low friction bearings to support and allow the turbine wheel to spin freely around the axle. All of the components that make up the turbine wheel assembly excluding the axle are securely joined together by various devices familiar to those with ordinary skill in the art. After the air passes through the turbine blades, the air exits  73  from the turbine wheel assembly and is then passed into the tail assembly  80 . A first end  67  of the axle is configured to secure to the inner end  49  of the nose backbone  46 . The second end  69  of the turbine axle is configured to secure to an inner end  87  of the tail backbone  86 . 
     Referring now to  FIG. 7 , an embodiment of the fixed vanes  50  of the nose assembly  40 , the turbine blades  70  of the turbine wheel assembly  60  and the fixed vanes  90  of the tail assembly  80  are shown. For the purpose of clarity, the cowlings designed to enclose the arrays of blades and vanes are not shown in  FIG. 7 . 
     As shown in  FIGS. 7 and 8 , the turbine assembly is configured such that the air passing over the aerodynamic nose  42  of the nose assembly  40  is directed through the array  51  of the fixed vanes  50  into the array  71  of turbine blades  70 . The turbine blades are configured to turn the airflow more than ninety degrees as it converts some of the kinetic energy of the accelerated wind into rotational power in the turbine wheel assembly  60 . The air stream is then discharged from the turbine wheel into array  91  of fixed vanes  90  configured in the tail assembly  80 . The air then flows past the aerodynamic tail  82  and turbine assembly  80 . As will be appreciated by those of ordinary skill in the art, the turbine blades may have various configurations currently known or to be developed, such as conventional air foil or “pinwheel” designs. 
     Referring now to  FIG. 8 , an embodiment of the fixed vanes  50  of the nose cone assembly  40 , the turbine blades  70  of the turbine wheel assembly  60  and the fixed vanes  90  of the tail assembly  80  are shown. The accelerated inlet air  120  enters the nose assembly between the fixed vanes. The entry space  130  between the vanes is configured for least resistance of the inlet fluid flow. The airflow space is then geometrically reduced by the redirecting curved vanes  50  to a lesser distance  132  so as to inverse proportionately accelerate the exit air from array  40  according to the Principle of Continuity. Thereafter, the accelerated air exits the nose assembly and enters the turbine assembly to contact the turbine blades, having a defined spacing  134  between the blades. The array  71  of curved vanes turns the air stream in excess of ninety degrees, and in the process absorbs a portion of the impact energy as a force on the blades to rotate the turbine wheel. The airflow  122  through the turbine blades then encounters a narrowed thrust space  136  to reaccelerate the exit air before it passes on to the tail assembly. The fixed vanes  90  of the array  91  turn the air stream to follow the wind and to eliminate energy absorbing trailing air swirl and lessen the backpressure of the exiting airflow  124 . As it will be appreciated by those of ordinary skill in the art, various configurations of the fixed vanes  50 ,  90  of the nose and tail assemblies and of the turbine blades  70  may be configured to optimize the performance of the turbine assembly. Similarly, various spacing  130 ,  132 ,  134 ,  136 ,  138  between the vanes and blades may be used to accommodate different shapes and sizes of the blades and vanes. 
     Referring now to  FIGS. 9 and 10 , the tail assembly  80  is configured with an inner end  87  of the pipe backbone  86  that is configured to mate with or otherwise attach to the second end  69  of the turbine axle  66  ( FIG. 5 ). The outer end  89  of the pipe backbone  86  is secured to a gusset  84  on the outside of the aerodynamic tail body  82 . A plurality of fixed vanes  90  in the tail assembly are configured to take the exit air from the turbine assembly and direct it through an inlet  83  and into the fixed vanes. As air passes through the exits  93  from the fixed vanes, it is then turned inward by the inwardly curved cowling  88  to follow the aerodynamic tail body  82  past the turbine assembly  30 . All of the nose assembly components are securely joined together by various means familiar to those with ordinary skill in the art. 
     Referring now to  FIGS. 11 and 12 , the turbine assembly of the present invention may be included within a helium inflated blimp assembly  200 . One embodiment of the blimp includes a nose section  202 , a tail section  204  and tail vanes  206 . As heretofore described, a standard turbine set  210  including the nose cowling and turbine wheel blades may be configured adjacent to a counter-rotating turbine set  212  including the tail cowling and turbine wheel blades. The blimp may be further configured with a pitch control cable  214  and tie down cables  216 ,  218  that are secured to a ground station or hanger  220 . The hanger may be configured to rotate along a track or turntable  222 . 
     The blimp assembly  200  version of the subject invention is a way of making very large laminar air turbines with the advantage of being able to fly it into faster, relatively smooth air above fifty feet elevation. The blimp assembly is configured to be lowered into the half dome hanger or shed  220  for protection from high winds and for periodic maintenances. The protective shed may be secured to a circular track turntable  222  that allows the shed to rotate and follow the blimp as it swings around to face the wind. Such an assembly would not require the typical huge windmill tower with expensive and deep foundations. 
     A composite design of the present invention is possible in which a medium sized inflated blimp-like body is used with laminar air turbine mounted on top of, or tethered to a tower. The blimp may be inflated with air, helium or other suitable gas. Alternatively, the turbine may be configured for underwater use. 
     In one embodiment of the present invention configured in a blimp assembly, the turbine wheel blades of turbine sets  210 ,  212  are configured to counter-rotate so as to cancel out their precessions and to reduce the tendency of the blimp to spin about its longitudinal axis. Referring now to  FIG. 13 , a generator system may be configured for use with the various embodiments of the turbine assembly  30  disclosed herein. Generator assembly  240  includes a generator  242  connected to bulkhead spokes  244 . A bulkhead rim  246  secures the generator to the assembly and secures a power transfer wheel  252  and/or idler wheels  254 ,  256  for extracting the power from the two counter-rotating turbines  250 . Another feature of the present invention that can be used in both the tower mounted turbine and the blimp embodiments of the present invention to secure the electric generators to the rim of a stationary bulkhead inside the body. Further, a number of power transfer wheels held between the two turbine wheels can be used to turn the generator shaft and generate electrical power and at the same time, equalizing the rotation rate of the counter-rotating turbines. As the wind speed increases, the wind drag would push the first turbine wheel against the power wheel forcing it against the drag resisting second turbine wheel for the positive frictional transfer of power. Depending on the turbine diameter, any number of electric generators could be mounted around the bulkhead rim and electrically switched on or off in sequence to match the available wind power. For example, when the wind speed is fifteen mph or less, only one generator may be needed to produce electricity. As the wind picks up speed, the additional generators would be switched on, one at a time, to generate more electricity and to prevent any overloading and burnout of generators from over-speeding turbine wheels. 
     While the specification illustrates and describes particular embodiments of the present invention, those of ordinary skill in the art of windmill design can devise various modifications of the present invention without departing from the inventive concept. For example, references to materials of construction and specific dimensions are also not intended to be limiting in any manner, and other materials and dimensions could be substituted and remain within the spirit and scope of the invention. Accordingly, it is not to be intended that the invention be limited, except as by the appended claims.