US5193978A – Articulated Blade With Automatic Pitch And Camber Control – Google Patents

If an external wind exists, the net force on the turbine is always in a forward direction. E. Automatic operation–no external controls or monitoring are required. Since its generator is also held aloft, a tall, and strong, support structure must be used. The cross-wind-axis turbine can be designed to have more or less self-supporting blades, and because its axis is stationary and vertical, its generator can be stationary and at ground-level. Current lift-drive, cross-wind-axis turbines have blades comprising fixed shape airfoils, symmetrical about straight chords, that is, with no camber, or, concavity. The former has its blades radiating out from a central axis, like a propeller. The cross-wind-axis turbine, having a stationary axis, has no axis-aligning mechanism to affect efficiency.

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REPOSA ESPALDA RELAX MASAJE - JOCCA Shop One cross-wind turbine, the cyclogiro, is considered to have a higher theoretical maximum energy conversion efficiency than wind-axis turbines. Currently designed cross-wind axis turbines do have drawbacks but to understand these drawbacks requires an analysis of the forces on these turbines. 4 shows the necessary parallelogram, indicated by the dotted lines, formed by these four rotational centers. These figures again show the distance relationships between the four rotational centerlines of hinge 14, and pins 18, 20, and 24. FIG. The articulated blade comprises a forward vane 10 and a rear deflector 12 connected by a hinge 14. Counterweight 26, running the span of the blade near the leading edge, is needed only when centrifugal forces arise, as when the blade is used on a turbine. The parallelogram linkage constrains deflector 12 to remain oriented parallel to control arm 16. Since control arm 16 is fixed parallel to the travel direction, deflector 12 always directs the flow in the best possible direction.

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In other words, lift would increase at pitch, if the exiting flow were directed still antiparallel to blade momentum. This force can be used for propulsion and has the advantage of a high lift to drag ratio. II. Low cost turbines using this invention can be built as wind breaks in areas where high winds are a problem. This is similar to drag-driven turbines, without the disadvantage of a high drag opposing forward motion, but also with the advantage of lift. This action automatically pitches the vane, reducing drag, but since the deflector is still oriented parallel to the control arm a force develops perpendicular to the push-pull direction. Dolor en la almohadilla de la planta del pie . Pin 24 is positioned to account for various forces but a reasonable starting position is, as shown, midway on the deflector. Cross-axis turbines can be driven by lift and/or drag forces. A. Self-starting. Drag and lift produce a high starting torque.

Wind gusts change blade pitch, preventing high drag. Once moving, pitch control can avoid stall caused by high drag on the blades. BACKGROUND–FIELD OF INVENTION This invention relates generally to wind turbines and more specifically to fluid deflecting blades and blade pitch control. This is represented by FIG. FIG. 5b shows conditions when blade speed equals wind speed (a speed ratio of one).

FIG. 5a shows the blade at startup when the speed ratio equals zero. FIG. 5a is for a blade speed of zero, at startup. Dolor lumbar costado derecho . It appears that with current blades, pitching is more for drag reduction than for increased lift. By controlling pitch, drag and lift can be used to start a turbine rotating. Drag-driven turbines, such as the savonius, are relatively inefficient because the drag force aids forward motion only through half a cycle, but impede on the other half cycle. 5b, are in the forward direction. FIG. 1 shows the vane at a zero pitch to the travel direction. FIGS. 5a-d are plan views of the blade at different blade speeds, with a wind speed greater than zero. Camber increases lift, but only if the wind is coming from one side of the blade, the concave side. But beyond that, cross-wind turbines are more easily stacked than wind axis turbines.

  1. Dificultad respiratoria
  2. Dos buenos aliados para controlar la tensión arterial
  3. Dolor y rigidez en el cuello
  4. Plumb the colder (input) water into the lower port on the center housing

Wind-axis turbines present circular areas to the wind, cross-wind axis turbines can present rectangular areas. Dolor muscular paracetamol o ibuprofeno . On aircraft, the wind generally hits the wings from below, but on cross-wind turbines the wind comes from either side. The difference here is that the vane doesn’t point into the wind except when the blade and wind direction are antiparallel.