Patent Application
20130292947
1. Field of the Invention
This invention relates to magnus rotors and more specifically to the use of magnus rotors as part of a system for generating electricity from wind energy.
2. Description of the Prior Art
It is generally accepted that a magnus rotor can only be revolved at about four times the wind speed for the purpose of converting wind energy into electrical energy. Experiments have shown this to be correct with the present technology. This is because as the magnus rotor is made to spin faster and faster aerodynamic drag is built up rather rapidly to the point where it takes more energy to revolve the rotor than the energy output from the system. Referring to U.S. Pat. No. 4,582,013 and the research upon which it is based as expressed in US Dept. of Energy Grant Report #DOE/R6/10969 we see various attempts to reduce aerodynamic drag. In FIG. 6 et alia of the patent we see the addition of a tail which is swung by the wind. This reduces turbulence downwind from the rotor. In the Grant Report there is described a “Circulator” to reduce induced drag. See page 16 of the report.
When the rotor is made to rotate, the top and bottom plates of the rotor also rotate and cause the air next to them to swirl, causing aerodynamic drag to be induced. The design of the “Circulator” imposes a mechanical barrier to prevent this circulation.
Also worth mentioning is the statement in U.S. Pat. No. 4,562,013 column 28, lines 33-35 “Wind tunnel tests show major improvements in aerodynamic performance due to the presence of shield 9, and due to aerodynamic seals.” The structure of this shield is explained in col. 28, lines 28-32.
Aerodynamic drag is directly dependant on the density of the atmosphere. Regardless of any other factor contributing to the increase in aerodynamic drag on a magnus rotor, reducing air density reduces aerodynamic drag. This reduction in the present invention is accomplished by sealing off the upper and lower plates and the half of the cylinder being rotated against the wind current, by an aerodynamic seal. A vacuum is made over these surfaces which is maintained during the operation of the rotor. Also, the interior volume of the rotor is originally built with a vacuum.
It is the principal object of the invention to reduce aerodynamic drag on a magnus rotor.
The attainment of the foregoing and related objects, advantages and features should be more readily apparent to those skilled in the art after the review of the following more detailed description of the invention, taken together with the drawing in which:
Turning to
In operation, as rotor 1 is made to spin liquid is urged from pipe 6 to pipe 7. The liquid is made to maintain a vacuum next to the endplates and half the radial surface of magnus rotor 1. Seals 5c,f also are made to maintain the vacuum of the interior volume of rotor 1. In this way the rotor may be spun faster for the same power input by motor 3. Calculating the drag force by seal 5 on rotor 1 The coefficient of kinetic friction of two oiled steel surfaces is 0.03-0.06. Assuming rotor 1 is rotated at a peripheral velocity of 1000 ft./sec. the normal force on rotor 1 by seal 5 may approach 1 bar, depending on the design of seal 5. The torque exerted by rotor 1 on shaft 2 (which may be substituted for a blade on a wind power turbine) is found by applying the Kutta-Joukowski formula.
From the above description it is apparent the embodiment achieves the principal object of the invention. The above embodiment is provided purely as an example. Many other variations, modifications and applications of this invention may be made. These are considered to be equivalent and within the spirit and scope of the invention.
