Tip vortex generation technology for creating a lift enhancing and drag reducing upwash effect

Utilizing a vortex pattern to improve performance of a foil:

• A method for improving the performance of a foil comprising providing relative movement between said foil and a fluid medium in a manner which creates a lifting force on said foil, and
• generating a substantially streamwise vortex pattern within said fluid medium, wherein
• said vortex pattern is positioned relative to said foil in an orientation effective to cause said fluid medium behind the trailing edge of said foil to experience a deflection away from the plane of said relative movement, and
• said deflection occurs substantially in the direction of said lifting force, wherein said deflection causes said lifting force to tilt forward in an amount effective to create a forward thrust component from said lifting force, whereby said forward thrust component substantially reduces the net effect of drag forces on said foil.

A low drag method for reducing vortex formation near the tip of a foil, comprising the steps of:

• (a) providing relative movement between said foil and a fluid medium in a manner which produces said vortex near the tip of said foil, wherein
• said vortex creates spanwise cross flow conditions substantially near said tip,
• (b) providing a control member mounted with mounting means to said tip of said foil in an orientation effective for reducing said spanwise cross flow conditions, wherein
• the interaction of said cross flow conditions and said member create a relative high pressure field within said fluid medium along a high pressure surface of said member and a relative low pressure field within said fluid medium along a low pressure surface of said member, and
• (c) reducing the angle of attack of said member relative to said cross flow conditions to achieve a substantial reduction in the pressure difference occurring between said high pressure surface and said low pressure surface in an amount effective to decrease turbulence formed along said low pressure surface near the tip portion of said member as said fluid medium flows around said tip portion from said high pressure surface toward said low pressure surface, and
• said decrease in turbulence significantly reduces drag on said member.

A method for improving the performance of a foil, comprising the steps of:

• (a) providing a plane of relative movement between said foil and a fluid medium, wherein
• said relative movement occurs in a manner which permits a relative decrease in pressure to occur within said fluid medium along a low pressure surface of said foil and causes a relative increase in pressure to occur within said fluid medium along a high pressure surface of said foil, wherein
• the difference in pressure between said high pressure surface and said low pressure surface creates a lifting force on said foil, and
• said lifting force is substantially directed from said high pressure surface toward said low pressure surface,
• (b) generating a beneficial vortex within said fluid medium which rotates around a substantially streamwise axis, wherein
• the direction of spin of said beneficial vortex around said streamwise axis causes said fluid medium inboard of said streamwise axis to rotate substantially in the direction of said lifting force, and
• the direction of spin of said beneficial vortex around said streamwise axis causes said fluid medium outboard of said streamwise axis to rotate substantially in the opposite direction of said lifting force, and
• (c) positioning said streamwise axis at a location near said tip which permits a majority of said fluid medium inboard of said tip to rotate substantially in said direction of said lifting force, wherein
• said beneficial vortex is sufficiently strong enough to cause a substantial portion of said fluid medium behind the trailing edge of said foil to experience a deflection away from the plane of said relative movement, and
• said deflection occurs substantially in said direction of said lifting force, whereby
• said vortex creates a substantial increase in said lifting force.

A method for encouraging a spanwise flow condition adjacent to a surface of a foil, comprising the steps of:

• (a) providing relative movement between said foil and a fluid medium so that said fluid medium flows in a substantially chordwise directed path across said surface of said foil,
• (b) providing a vortex generating means for generating at least one vortex within said fluid medium, and
• said vortex generating means is attached to said surface with an attachment means which is arranged to permit said vortex generating means to generate said vortex within a predetermined height above said surface, wherein
• said vortex rotates around a substantially chordwise axis, and
• said chordwise axis substantially divides said fluid medium above said surface into
• a lower portion of said fluid medium which exists between said surface and said chordwise axis,
• an upper portion of said fluid medium which exists between said chordwise axis and said predetermined height, and
• a free stream portion of said fluid medium which exists above said predetermined height, and
• (c) arranging the orientation of said generating means relative to said surface in a manner which causes said vortex to rotate around said chordwise axis in a direction that permits said upper portion of said fluid medium to flow in a predetermined spanwise direction relative to said surface in an amount effective to cause a substantial volume of said free stream portion of said fluid medium to achieve a net cross flow condition relative to said surface, wherein
• said net cross flow condition occurs substantially in said predetermined spanwise direction, and
• said predetermined spanwise direction is selected to improve the performance of said foil.

A foil tip comprising:

• (a) an inboard end having mounting means for mounting to an outboard end of a foil,
• (b) said foil tip and said foil having relative movement to a fluid medium, and
• (c) said foil tip having an upper surface and a lower surface relative to the plane of said relative movement, wherein
• said upper surface is adjacent to the low pressure surface of said foil and said lower surface is adjacent to the high pressure surface of said foil, and
• said upper surface and said lower surface bend substantially around at least one rearwardly divergent axis to form a divergent anhedral tip droop relative to said high pressure surface of said foil, wherein
• said upper surface transforms into an outboard droop surface existing substantially outboard of said divergent axis,
• said lower surface transforms into an inboard droop surface existing substantially outboard of said divergent axis, and
• said outboard droop surface and said inboard droop surface terminate at an outboard edge of said foil tip so that at least a portion of said outboard edge of said foil tip is substantially below the plane of said lower surface of said foil tip existing between said inboard end and said divergent axis, wherein said divergent axis is sufficiently divergent enough from said direction of said relative movement to cause a relative increase in pressure within said fluid medium along said outboard droop surface in an amount effective to create an inboard cross flow within said fluid medium below said outboard end of said foil tip, wherein
• said inboard cross flow moves toward said high pressure surface of said foil to create an increase in pressure within said fluid medium existing along said high pressure surface of said foil.

A flap system, comprising:

• (a) a foil having relative movement to a fluid medium in a manner which creates a lifting force on said foil,
• (b) a vortex flap having an inboard end, an outboard portion, a leading portion, a trailing portion, and two substantially opposing surfaces, and
• (c) an adjustable mounting means for mounting said inboard end of said vortex flap to the outboard end of said foil, wherein
• said adjustable mounting means is arranged to permit said vortex flap to pivot around a divergent axis, to a predetermined angle of attack thereby enabling said vortex flap to generate a vortex pattern within said fluid medium which is capable of creating a net deflection within said fluid medium behind the trailing edge of said foil, wherein said net deflection occurs substantially in the direction of said lifting force on said foil.