Patent Publication Number: US-2009232654-A1

Title: Andrews turbine

Description:
The Andrews Turbine is a relatively simple vertical axis turbine design that can be utilized to extract energy from nature for the purpose of generating electricity. The Andrews Turbine contains many new and revolutionary design features that eliminate many of the short comings of present vertical axis wind turbines. The design of the blades is new and offers many advantages over past designs. The overall configuration of the Andrews Turbine with a vertical axis and horizontal blade is revolutionary and allows the turbine to occupy a small volume while delivering enough power to drive a high ratio gearbox. The power can be increased by adding rotor sets to the turbine, while still maintaining a relatively small package. The combination of the new design features allows the Andrews Turbine to generate electricity from either wind or water without changing the design or components. FIGS.  4 / 8  and  5 / 8  illustrate the components of the Andrews Turbine. 
    
    
     
       Blades: FIG.  1 / 8   
       The blades are thinner on the leading edge than the trailing edge and the interior of the blade is hollow or concave. The blades are designed to offer more resistance on the trailing edge than the leading edge, this keeps the blade rotating in the same direction. The length, width and height of the blade can vary, depending on application and materials. 
       The Andrews Turbine can rotate either clockwise or counterclockwise, depending on the orientation of the blades. The power of the Andrews Turbine is increased by adding additional blades, this does not increase the speed of the drive axle but rather the amount of torque transferred to the drive axle. 
       Vertical Partitions: FIG.  1 / 8   
       Each blade in an Andrews Turbine has vertical partitions within the concave portion of the blade. The number and spacing of the vertical partitions can vary, depending on size and application. The purpose of the vertical partitions is to create directed turbulence within the interior of the blade which extracts more energy from the environment. The energy generated by the turbulence is transferred to the drive axle in the form of torque. 
       Blade Strut: FIG.  1 / 8   
       The blades struts attach the blades to the hubs. If the hubs are not used, the blade struts would attach the blades directly to the drive axle. 
       Hub: FIG.  2 / 8   
       The hub is a device to attach the blades to the drive axle in a symmetrical pattern. The hubs are symmetrical with a hole in the middle for attaching the hub to the drive axle, the blades are attached to the sides of the hub. When attaching the hub to the drive axle the hubs are offset from adjacent hubs (FIG.  3 / 8 ), resulting in evenly spaced blades around the drive axle (FIG.  4 / 8 ). This eliminates the requirement to orient the turbine into the changing wind direction. 
       Drive Axle: FIG.  5 / 8   
       The drive axle transfers the energy generated by the blades to the gearbox/generator. The drive axle is oriented in a vertical position while the blades are horizontal. The drive axle can rotate in a clockwise or counter clockwise direction and is directly attached to the gearbox. 
       Rotor Set: FIGS.  4 / 8  and  5 / 8   
       A rotor set is a group of blades and hubs offset from one another such that there is a symmetrical distribution of the blades around the drive axle and no two blades are in the same vertical plane. FIG.  3 / 8  illustrates that with a three sided hub that is offset from adjacent hubs by 30° four hubs are required to provide a complete and symmetrical pattern of blades through a 360° circle. In this example there are four hubs and twelve blades to a rotor set. A hub with a different design would have a different number of hubs and blades in each rotor set. When increasing the power of an Andrews Turbine it is best to add additional blades as a rotor sets in order to provide a balanced distribution of power. 
     
    
    
     Andrews Wind Turbine 
     The Andrews wind turbine is a vertical axis wind turbine (VAWT). There are two general types of wind turbines, horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT). So far the HAWT&#39;s have been the more successful and best known wind turbine. The HAWT consists of two or more blades, a gearbox, generator, and auxiliary motors, sensors and mechanisms. To increase efficiency, they are mounted on tall towers to take advantage of faster and less turbulent winds with altitude. The blades are designed to provide lift, enabling the blades to turn faster than the wind velocity. Currently all utility and most small applications are HAWT design. 
     There are inherent disadvantages to the HAWT design that increases complexity, therefore the cost and reliability, of the HAWT turbine. The blades must be precisely manufactured to provide maximum lift. In high winds the blades must be retarded by changing the pitch of the blade and by braking the drive axle. The blades must also be reoriented into the wind as the wind changes direction. The gearbox must be robust because it bears the weight of the blades and drive axle. The mechanical complexity of HAWTs increases the cost to manufacture and maintain the equipment. Other problems with HAWTs are the noise they create and the large number of birds killed by the blades. The public outcry has affected the acceptance and locations of some HAWT projects. 
     Generally most VAWTs are of two basic designs. The Darrius turbine has two long vertical blades mounted on a vertical shaft. The Giromill turbine is a variation of the Darrius turbine. The Giromill turbine has two or more vertical blades which can be straight, y-shaped or curved. The Savonious turbine has two or more vertical, scooped shaped blades driving a vertical axis. These blades are usually mounted near the ground. 
     The advantages of VAWTs derive from its vertical axis. The foundation or generator bears the weight of the blades and drive axle allowing for a less robust gearbox. Because the blades are symmetrical about the axle, there is no requirement to orient the blades into the wind. The simplicity of design greatly reduces the cost of manufacturing and maintaining VAWTs. One shortcoming of the VAWT is the difficulty of mounting them on a tall tower. The blades are generally a drag type design allowing the blades to turn no faster than the wind speed. VAWTs are difficult to start in low wind speeds because of the limited torque which also makes high ratio gearboxes impractical. Increasing the size of the VAWTs without developing a pulsating torque has proven difficult. 
     The Andrews Turbine is a revolutionary new design because while the drive axle is vertical, the blades are horizontal (FIGS.  4 / 8  and  5 / 8 ). By mounting the blades horizontally it is possible to mount numerous blades in a relatively small volume. The Andrews Turbine retains all the beneficial characteristics of VAWTs such as simplicity of manufacturing and maintenance, while overcoming the shortcomings such as mounting on tall towers, starting in low winds and driving a high ratio gearbox. 
     Regardless of application, the Andrews Turbine consists of two or more blades (FIGS.  1 / 8  and  2 / 8 ) symmetrically attached to the hub. Two or more blades attached to the drive axle (FIGS.  3 / 8  and  4 / 8 ). The blades are elongated with the leading edge narrower than the trailing edge and are concave along its length with partitions at each end and with one or more partitions within the hollow part of the blade (FIG.  1 / 8 ). These partitions create turbulence within the concave portion of the blade which results in increased energy transfer to the blade. Because blades are symmetric about the hub and are in the same horizontal plane (FIG.  2 / 8 ), the hub us designed so the blades do not interfere with the air flow to the other blades. When attaching the hubs to the drive axle, the hubs are offset from the hubs above and below allowing full 360° coverage (FIG.  3 / 8 ). 
     In order to increase the output of any turbine it is necessary to increase to horsepower of the turbine. One horse power is equivalent to 746 watts and is expressed as torque X rpm/63,000. To date manufacturers increase the horsepower of wind turbines by increasing the size and speed of the blades and by using high ratio gearboxes. Observations during tests of the Andrews Turbine show that as hub assemblies are added, the rpm remains the same but the force needed to brake the drive axle increases, indicating an increase in torque. The horsepower of the Andrews Turbine is increase by increasing the torque of drive axle not by increasing the rpms. The ability to turn slowly with high torque makes the Andrews Turbine superior mechanically to other designs and lends itself to multiple applications. 
     The Andrews Turbine for small applications can have blades approximately three feet long and two inches high at the trailing edge. If each blade is mounted six inches from the centerline of the drive axle the blades define a seven foot diameter of rotation. Using a hub that is an equilateral triangle three blades can be attached to the hub without the blades interfering with the air flow to other blades on the same horizontal plane. With this arrangement, the hub and three blades are referred to as a hub assembly (FIG.  2 / 8 ). When attaching the hub assemblies to the drive axle each hub assembly is rotated 30° from the adjacent hub assembly resulting in a complete 360° coverage with four hub assemblies (FIG.  3 / 8 ). These four hub assemblies (12 blades) are referred to as a rotor set (FIGS.  4 / 8  and  5 / 8 ). With this example each rotor set occupies a cylindrical volume of seven feet in diameter and sixteen inches high and contains the equivalent of three blades with a turning diameter of twenty-eight feet. By mounting three rotor sets in a cylindrical volume of seven feet in diameter and five feet in height, you have the equivalent of three blades with a turning diameter of eighty-four feet. The small volume occupied by the turbine allows for mounting on a tall tower and the installation of a screen to keep birds away from the blades (FIG.  6 / 8 ). The slow turning blades do not create noise and the high torque allows for a high ratio gearbox which can turn the generator fast enough to generate electricity. 
     Because the Andrews Turbine can generate high torque while turning slowly, the Andrews Turbine can also be powered by water flow even if the current is slow. The blades with the vertical partitions can generate enough torque to keep the drive axle turning in a constant direction. While the drive axle is turning slowly, the high ratio gearbox can turn the generator fast enough to generate electricity. The design of the Andrews Turbine for hydroelectric applications is the same as for wind generation (FIG.  7 / 8 ). 
     With two hub assemblies each containing three blades and rotated 180° from each other, the Andrews Turbine can be mounted on the top of a vehicle (FIG.  8 / 8 ). Using 16 inch long and 1 inch high blades, the complete turbine would measure 3 feet in diameter and 3 inches high. This vehicle turbine could trickle charge batteries whether the vehicle is moving or not. The turbine would not interfere with the operation of the vehicle. The gearbox and generator can be mounted under the roof or on top of the turbine. 
     The Andrews Turbine is capable of extracting energy from nature utilizing several mediums. The Andrews Turbine is made up of numerous horizontal blades symmetrically distributed about a vertical drive axle (FIGS.  4 / 8  and  5 / 8 ). Vertical partitions within the blades (FIG.  1 / 8 ) are necessary for extracting maximum energy from either wind or water.