WO1988010210A1

WO1988010210A1 - Venturi enhanced airfoil

Info

Publication number: WO1988010210A1
Application number: PCT/US1988/002102
Authority: WO
Inventors: Mark T. Willis
Original assignee: Willis Mark T
Priority date: 1987-06-25
Filing date: 1988-06-23
Publication date: 1988-12-29
Also published as: BR8807113A; AU2325988A; JPH02501213A; EP0319574A4; EP0319574A1; KR890701417A

Abstract

A basic airfoil has its operating performance improved by incorporating one or more apertures in the airfoil adjacent its trailing edge. These apertures (24) extend from the upper surface (18) of the airfoil down through to the lower surface (20) of the airfoil. The entry port (25) and the exit port (26) of these apertures (24) has a greater circumference than that of the throat (27) circumference which is intermediate thereto. This structure forms a venturi having a vertical axis. Spaced below the throat (27) of the aperture (24) are a plurality of air nozzles (30) that communicate with an air plenum chamber (32) within the airfoil. A source of pressurized air (35) is connected to the plenum chamber (32). The venturi enhanced airfoil can be utilized both in a horizontal fixed airfoil or its structure can also be incorporated into the tail rudder (53) of an aircraft or helicopter. The venturi enhanced airfoil can be oriented in any position between the horizontal and vertical axes.

Description

VENTURI ENHANCED AIRFOIL

Technical Field

The invention relates to an airfoil and more specifically to an airfoil having a venturi assembly incorporated therein adjacent the trailing edge of the airfoil to enhance its performance.

Background Art

Since the early days of the invention of the airplane, there has been a continuous effort to improve the lift characteristics of the airfoils of an aircraft. The airfoil configuration of the wings are varied according to " the desired performance required by the aircraft.

Some attempts have been made to incorporate novel structure into the wing itself to enhance its lift performance. One such example is that of the rotor augmented wing illustrated in U.S. patent number 3,372,891. In this patent the inventor has incorporated a semicircular recess in its trailing edge and has mounted a powered rotor therein about the axis of the recess. The rotor produces direct upward thrust on the aircraft and also creates low pressure over the wing and higher pressure below the wing to augument the the direct upward thrust of the rotor.

SUBSTITUTE SHEET Disclosure of Invention

Applicant's novel venturi enhanced airfoil has application in both a fixed horizontal airfoil of an aircraft or its structure may be incorporated into the vertical rudder of the tail section of an aircraft or helicopter. In the fixed horizontal airfoil application, the leading edge of the airfoil causes airflow across both the upper and lower surface of the airfoil. The velocity of the air passing over the upper surface of the airfoil is greater that that passing beneath its lower surface thereby causing a lower pressure on the top surface of the airfoil which results in lift of the airfoil itself in a static condition. Applicant's novel venturi assembly is incorporated into the airfoil structure adjacent the trailing edge thereof. The venturi has an entry port at its upper end, an exit port at its lower end, both of which have a greater circumference than the throat portion intermediate its top and bottom end. A plurality of air nozzles are spaced around the circumference of the venturi at a position between the throat and the exit port thereof. These air nozzles are in communication with a plenum chamber within the airfoil that is supplied with pressurized air from either the engine of the aircraft or some auxiliary source. This produces an air driven venturi which creates a strong suction on the upper surface of the airfoil. This further increases the velocity of the air passing over the top surface of the airfoil to further decrease the pressure on the top side of the airfoil. The air which has been sucked down through the venturi assembly further increases the high pressure force on the bottom of the airfoil and also slows the velocity of the air passing along the lower surface of the airfoil. The combination of these different forces results in additional lift performance for the airfoil itself.

SUBSTITUTE SHEET The venturi assembly has a vertical axis and this axis can be incorporated into the airfoil at an angle with respect to the horizontal axis of the airfoil between a range of two degrees to twenty degrees. This inclination results in a vectored thrust in the forward direction that the wing would be traveling in. The geometrical configuration of the venturi's aperture can be circular, elongated oval shaped, or other desired geometrical shapes. There may be more than one venturi assembly formed adjacent the trailing edge of an airfoil.

The venturi enhanced airfoil can also be incorporated into the rudder of the tail of an aircraft or helicopter. The rudder can have either a single venturi assembly incorporated therein or multiple venturi assembly incorporated therein. Additionally one venturi assembly could have its • entry port on one vertical side of the airfoil and the other venturi assembly could have its entry port on the opposite side of the airfoil. In the arrangement having the entry ports on opposite sides of the airfoil, they can create their suction effects on both sides of the airfoil, which in turn can move the airfoil in either direction in a static condition. This effect can be created by increasing and decreasing the pressurized airflow in the particularly desired venturi in order to move the airfoil in the direction so desired. One application for this detailed structure would be to use it to replace the current tail rotor system of a helicopter. In this type of embodiment, the exhaust gas from the turbine of the helicopter can be ducted to the front of the verticle venturi enhanced airfoil which will be mounted on the end of the helicopters tail boom. In this configuration the enhanced airfoil will act as a rudder with the enhanced pressure differential acting against the main rotor torque.

SUBSTITUTE SHEET Brief Description of Drawings

Figure 1 is a partial top plan view illustrating applicant's novel venturi enhanced airfoil;

Figure 2 is a schematic cross-sectional elevation view taken along lines 2-2 of Figure 1 ;

Figure 3 is a partial top plan view illustrating a first alternative venturi enhanced airfoil;

Figure 4 is a schematic cross-sectional elevational view taken along lines 4-4 of Figure 3;

Figure 5 is a schematic illustration that indicates how air is supplied to the venturi assemblies.

Figure 6 is a side elevation view of the venturi enhanced airfoil utilized in the tail of an aircraft;

Figure 7 is a horizontal cross section taken along lines 7-7 of Figure 6;

Figure 8 is a first alternative embodiment ^"of the venturi enhanced airfoil utilized in the tail of an aircraft ;

Figure 9 is a horizontal cross-sectional view taken along lines 9-9 of Figure 8;

Figure 10 is a horizontal cross-sectional view taken along lines 10-10 of Figure 8; and

Figure 11 is a partial cross-sectional view illustrating a modified venturi assembly in the horizontal fixed airfoil of an aircraft.

Best Mode for Carrying Out the Invention

Applicant's novel venturi enhanced airfoil will now be described by referring to Figures 1-11 of the drawings. In Figure 1 the fixed wing airfoil is generally designated numeral 16. It has a leading edge 17, a trailing edge 18, an upper surface 19, and a lower surface 20. A deflector cap 22 is mounted adjacent and covering leading edge 17. A venturi assembly 24 is located adjacent trailing edge 18. A

SUBSTITUTE SHEET plenum chamber 21 is positioned in leading edge 17 and pressurized air is released through orifice 21a to travel over both the respective upper and lower surfaces 19 and 20. Venturi assembly 24 has an entry port 25, an exit port 26, and a throat 27. Venturi assembly 24 has a vertical x-axis with respect to the y-axis. The y-axis has a forward inclination with the x-axis and this may be designated between the range of two to twenty degrees. Positioned slightly below throat 27 are a plurality of air nozzles 30 that are in communication with a plenum chamber 32. Conventional ducting (not shown) would be connected to plenum chamber 32 from a source of prsssurized air, such as the exhaust of the aircraft. A schematic illustration of such a system is illustrated in Figure 5 where numeral 35 identifies a source of pressurized air.

The airfoil illustrated in Figure 3 is designated numeral 40. It has a leading edge 41, a trailing edge 42, an upper surface 43, and a lower edge 44. It has a plurality of venturi assemblies 45 and these have an elongated oval-shape. Each of them have an entry port 47, an exit port 48, and a throat 49. Air nozzles 50 are in communication with plenum chamber 52.

In Figure 6 an embodiment is illustrated that shows the venturi enhanced airfoil incorporated into the tail 53 of the fuselage 54 of an aircraft. The aircraft may be a fixed airfoil type of conventional aircraft or it may be the tail of a helicopter. Airfoil 56 functions as the rudder and it pivots about an axis 58. Utilizing the same descriptive designations to airfoil 56 as that of the horizontally oriented airfoils, it has a leading edge 60, a trailing edge 61, an upper surface 62, and a lower surface 63. The venturi assembly 65 has an entry port 66, an exit port 67, and a throat 68. A plurality of air nozzles 70 are in communication with a plenum chamber 72. Plenum chamber 72 would have conventional ducting from a pressurized air supply source.

SUBSTITUTE SHEET In Figures 8-10, a first alternative embodiment of the vertically oriented venturi airfoil is illustrated. Its airfoil 75 has a leading edge 76, a trailing edge 77, an upper surface 78, and a lower surface 79. An upper venturi assembly 80 has its entry port 81 on one side of airfoil 75 while the lower venturi assembly 90 has its entry port 91 on the opposite side. Venturi assembly 80 also has an exit port 82, a throat 83, air nozzles 84 and a plenum chamber 85. Likewise lower venturi assembly 90 also has an exit port 92, a throat 93, air nozzles 94, and a plenum chamber 95.

A modified structure of a venturi assembly 100 is illustrated in Figure 11 in a horizontal fixed wing. It has an entry port 101, an exit port 102, and a throat 103. A plurality of air nozzles 104 are in communication with a plenum chamber 105. Deflector vanes 107 are pivoted on hinge 108 and can be actuated together in coordinated travel to vary the direction of the air flow exiting venturi assembly 100.

It is to be noted that applicant's novel airfoil construction could be used on a water vehicle to aid in lifting its hull partially or entirely out of the water. It would also provide forward thrust.

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Claims

1. In a vehicle, a venturi enhanced airfoil comprising : an airfoil having a leading edge, a trailing edge, and upper and lower surfaces, said airfoil . having a substantially horizontal axis; a venturi assembly having a vertical axis, said venturi assembly having an entry port and an exit port each having a predetermined circumference, a throat portion is formed intermediate said entry port and said exit port and it has a circumference less than that of either said entry port and said exit port, said venturi assembly being located in said airfoil adjacent its trailing edge, said venturi being powered by producing a low pressure zone in the lower end of said venturi assembly in the direction of the high pressure surface of said airfoil thereby causing air from the low pressure surface of said airfoil to flow to the high pressure surface of said airfoil, the region on said airfoil opposite the low pressure zone of said venturi increases the velocity of the air moving across the upper surface of said airfoil, the stated increase in velocity decreases the absolute pressure on the upper surfaces of said airfoil whereby the flow of air through the venturi produces a thrust force in the direction of the upper surface of said airfoil thereby slowing the velocity of the air on the lower surface of said airfoil thus increasing the absolute pressure on the lower surface of said airfoil thereby producing an increase in lifting force due to increased pressure differential between the upper and lower surface of said airfoil.

2. A venturi enhanced airfoil as recited in claim 1 wherein the entry port of said venturi assembly has a circular geometrical shape.

SUBSTITUTE SHEET

3. A venturi enhanced airfoil as recited in claim 1 wherein the entry port of said venturi assembly has an elongated oval—shaped geometrical shape.

4. A venturi enhanced airfoil as recited in claim 1 wherein said airfoil has more than one venturi assembly formed in it adjacent its trailing edge.

5. A venturi enhanced airfoil as recited in claim 1 further comprising a plurality of air nozzles around the perimeter of said venturi assembly in the zone between said throat portion and said exit port.

6. A venturi enhanced airfoil as recited in claim 5 further comprising a plenum chamber associated with said air nozzles.

7. A venturi enhanced airfoil as recited in claim 5 further comprising a source of pressurized air in communication with the air nozzles of said venturi assembly.

8. A venturi enhanced airfoil as recited in claim 1 wherein the vertical axis of said venturi assembly intersects the horizontal axis of said airfoil at an angle between 2 degrees and 20 degrees.

9. A venturi enhanced airfoil as recited in claim 1 wherein said airfoil has a diverter mounted in front of its leading edge, said leading edge having a slot formed in it that is in communication with a plenum chamber adjacent said leading edge.

10. A venturi enhanced airfoil as recited in claim 1 further comprising means positioned adjacent the exit port of said venturi assembly for controlling the direction of travel of the air exiting therefrom.

11. An airfoil having a leading edge, a trailing edge, a low pressure surface, and a high pressure surface;

SUBSTITUTE SHEET a venturi assembly having an entry port and an exit port each having a predetermined circumference, a throat portion is formed intermediate said entry port and said exit port and it has a circumference less than that of either said entry port and said exit port, said venturi assembly being located in said airfoil adjacent its trailing edge, said venturi assembly being powered by producing a low pressure zone in the lower end of said venturi assembly in the direction of the high pressure surface of said airfoil thereby causing air from the low pressure surface of said airfoil to flow to the high pressure surface of said airfoil, the region on said airfoil opposite the low pressure zone of said venturi assembly increases the velocity of the air moving across the low pressure surface of the airfoil, the stated i ncrease in velocity decreases the absolute pressure on the low pressure surface of said airfoil whereby the flow of air through the venturi produces a ζhrust force in the direction of the low pressure surface of said airfoil thereby slowing the velocity of the air on the high pressure surface of said airfoil thus increasing the absolute pressure on the high pressure surface of said airfoil thereby producing an increased perpendicular force due to the increased pressure differential between the low and high pressure surfaces of said airfoil.

12. An airfoil as recited in claim 11 wherein it is mounted in the tail of an aircraft.

13. An airfoil as recited in claim wherein the entry port of said venturi assembly has an elongated oval-shaped geometric shape.

14. An airfoil as recited in claim 11 wherein said airfoil has more than one venturi assembly formed in it adjacent its trailing edge.

SUBSTITUTE SHEET

15. An airfoil as recited in claim 14 wherein the entry port of one of said venturi assemblies is located on the high pressure surface of said airfoil and the entry port of another of said venturi assemblies is located on the low pressure surface of said airfoil.

16. An airfoil as recited in claim 11 further comprising a plurality of air nozzles around the perimeter of said venturi assembly in the zone between said throat portion and said exit portion.

17. An airfoil as recited in claim 16 further comprising a plenum chamber associated with said air nozzles.

18. An airfoil as recited in claim 16 furhter comprising a source of pressurized air in communication with the air nozzles of said venturi assembly.

SUBSTITUTE SHEET