Fluid energy converting method and apparatus
First Claim
1. A method for converting the kinetic energy of a fluid stream into useful work comprising the steps of positioning a device including a pair of parallel plates and a thin airfoil equally spaced from each plate and having at least two degrees of freedom within a moving fluid stream with the plates parallel to the free stream and the airfoil at zero angle of attack when undisturbed to define an aerodynamic system, adjusting the system until the velocity of the fluid is sufficient to induce flutter oscillations, disturbing the airfoil, and then utilizing the resultant oscillations to produce useful work.
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Abstract
There is disclosed a method and apparatus for converting the kinetic energy of a moving fluid stream into useful work by means of a cascade of thin airfoils positioned therein. In one embodiment, the airfoils are provided with at least two degrees of freedom and adjacent airfoils are movable out of phase. The airfoils are subjected to the aerodynamically induced oscillations caused by the aeroelastic phenomenon known as flutter and the oscillatory movement is then harnessed to do useful work. In an alternate embodiment, a cascade of airfoils is mechanically oscillated within a moving fluid stream to increase the propulsion of the fluid. Where the fluid is a liquid, the cascade includes a plurality of hydrofoils.
55 Citations
33 Claims
- 1. A method for converting the kinetic energy of a fluid stream into useful work comprising the steps of positioning a device including a pair of parallel plates and a thin airfoil equally spaced from each plate and having at least two degrees of freedom within a moving fluid stream with the plates parallel to the free stream and the airfoil at zero angle of attack when undisturbed to define an aerodynamic system, adjusting the system until the velocity of the fluid is sufficient to induce flutter oscillations, disturbing the airfoil, and then utilizing the resultant oscillations to produce useful work.
- 14. Apparatus for converting the kinetic energy of a fluid stream into useful work comprising a support structure open at opposite ends to permit fluid flow therethrough and including a plurality of equally spaced flat plates extending parallel to the direction of fluid flow, a plurality of airfoils, means for mounting said airfoils within said support structure in a cascade with each airfoil having at least two degrees of freedom and being equally spaced between adjacent flat plates at zero angle of attack when undisturbed, means interconnecting said airfoils to oscillate in phase, and means operatively associated with said airfoils to utilize the oscillatory movement thereof to produce useful work.
Specification