| 摘要 |
An airfoil or hydrofoil 30 arranged for use in a fluid flow of varying direction relative to the airfoil has arranged thereon a plural axis hinge 50 for automatic adjustment of the angle of pitch of the airfoil. The hinge 50 may comprise a fixed plate attached to a fairing 60 and a movable plate 55 attached to the foil 30; pivoting cross-links 56, 58 may extend between the plates 56, 58. The movement of the airfoil form one hinge axis to the other may be immediate or gradual. The fluid may be water and the flow may be tidal, wave or river or ocean currents. The airfoil can be applied to a rotary crossflow device for use in a fluid flow of varying apparent flow direction, an oscillating device for use in a fluid flow, a force generation device for use in a fluid flow of varying direction, or a flow control device for use in a fluid flow of alternating direction. The device may be an oscillating propulsor, eg a sculling oar or a swimming aid. The plural axis hinge may aid "end of stroke turning" of the foils (fig.21). |
