초록 ▼

Wing tip vortices are evident from airliner vapor trails, and helicopter blade slap. Elliptically loaded high aspect ratio tapered wings have minimum induced drag but cannot eliminate it. Different methods are disclosed herein, for upper and lower surface boundary layers to cancel their opposing vor

Wing tip vortices are evident from airliner vapor trails, and helicopter blade slap. Elliptically loaded high aspect ratio tapered wings have minimum induced drag but cannot eliminate it. Different methods are disclosed herein, for upper and lower surface boundary layers to cancel their opposing vorticity upon shedding from the trailing edge, thereby eliminating wake vorticty, induced drag and associated noise. This requires wing-rotor-propeller or fan blades with a platform designed for uniform bound circulation and with boundary layer control near the tip. In addition this requires special techniques to counter span-wise pressure gradients, such as tip circulation control blowing or an upwind small propeller or wind turbine on each tip. These techniques can eliminate wake vorticity with its induced drag, noise, flying on the backside of the power curve and the option for asymmetric loading by pneumatic means to eliminate need for cyclic pitch control or conventional ailerons.

대표청구항 ▼

I claim: 1. An apparatus comprising: a lift producing finite wing comprising a finite semi-span ending in a tip, with an upper surface, a lower surface, a leading edge, and a trailing edge; the wing moving through a fluid, the fluid having an undisturbed, free stream velocity relative to the wing;

I claim: 1. An apparatus comprising: a lift producing finite wing comprising a finite semi-span ending in a tip, with an upper surface, a lower surface, a leading edge, and a trailing edge; the wing moving through a fluid, the fluid having an undisturbed, free stream velocity relative to the wing; one or more boundary layer control suction slots positioned near the tip of the finite wing parallel and in close proximity to the trailing edge in at least one of the upper surface, the lower surface or the trailing edge itself; one or more boundary layer control suction slots positioned near the tip the wing in the chordwise direction and in close proximity to at least one of the upper surface, the lower surface and the tip itself; at least one vacuum source lowering the pressure inside the suction slots to below that found on the surrounding lifting surfaces and pneumatically connected to at least one of the boundary layer control suction slots; and operation of at least one vacuum source to capture by suction most of the upper and lower surface boundary layer vorticity within the proximity of the wing tip, prior to shedding the remaining boundary layer at the trailing edge, thereby substantially reducing spanwise pressure gradients over the tip portion of the lift producing finite wing and substantially eliminating shedding of boundary layer vorticity from the wing. 2. The apparatus in claim 1 wherein at least one vacuum source comprises at least one of an ejector, a mechanical movement type vacuum pump or pumping action of a propeller with the ability to dissipate internally, by viscous means, the captured boundary layer vorticity. 3. The apparatus in claim 1 wherein the at least one vacuum source discharges mass flow captured by the suction slots, in the form of a wall jet to improve alignment of the wing upper and lower surface boundary layer velocities with the direction of the free stream velocity by directing said wall jet tangentially to a rounded wing tip end which is positioned substantially in the chordwise direction, such that the wall jet attaches to the rounded wing tip surface by Coanda effect and the wall jet flows in the general direction from the upper surface towards the lower surface of the wing. 4. The apparatus in claim 1 wherein the at least one vacuum source discharges mass flow captured by the suction slots, in the form of a jet in parallel to the end surface of the tip and substantially in the chordwise direction while originating in the vicinity of the tip leading edge. 5. The apparatus in claim 1 wherein the inner region of the wing is shaped such as to substantially generate a substantially uniform loading in order to maximize alignment of the wing upper and lower surface boundary layer velocity in the free stream velocity direction, thereby maximizing the effectiveness of boundary vorticity capturing and dissipation within suction slots positioned in the proximity of the wing tips. 6. The apparatus of claim 1 further comprising a minimized tip region area by the application along the tip region extremity of one of a boundary layer suction slot, a fence, or circulation control by blowing over a rounded surface. 7. The apparatus of claim 1, applied to a rotor blade, where one or more suction slots are installed along or in the vicinity of the blade trailing edge to capture most of the vorticity contained within upper and lower surface boundary layers of the blade and dissipate the captured vorticity, by viscous means, with one of an ejector type compressor, a mechanical type compressor, or other mechanical means, prior to venting captured mass flow back into the wake, in order to minimize wake vorticity with its associated downwash velocity, induced drag and noise. 8. The apparatus of claim 1, applied to a rotor blade, where one or more suction slots are installed in the chordwise direction along at least one of the upper and lower surface of the rotor blade along the common boundary between an inner span region and tip region, for the purpose of minimizing spanwise pressure gradients which interfere with usual vorticity cancellation between upper and lower surface boundary layers when shed at the trailing edge of the inner span region of said lifting surface. 9. The apparatus of claim 1, applied to a rotor blade, comprising of a minimized tip region area wherein said boundary suction is provided via internal ductwork to a mechanical compressor(s) or ejector pump, capable of dissipating the captured vorticity and discharging an non-rotational flow back into the wake or via a circulation control jet positioned along the extremity of the tip region.