System and method for enhancing the high-lift performance of an aircraft
A drag reduction system for an aircraft may include an air ejector having an ejection port located between an aft portion of an airfoil main element and a forward portion of a trailing edge device. The air ejector may be configured to discharge an air jet from the ejection port in such a manner that the air jet passes over the upper surface of the trailing edge device.
1. A drag reduction system for an airfoil, comprising:
an air ejector having an ejection port mounted on or extending aftwardly from an aft portion of an airfoil main element of the airfoil, the ejection port terminating within a main cove having side boundaries defined by the aft portion of the airfoil main element and a forward portion of a trailing edge device and an upper boundary defined by an overhang extending from the aft portion of the airfoil main element, the election port terminating at a location below the overhang; and
the air ejector configured to discharge an air jet from the ejection port in such a manner that the air jet is discharged into the main cove and mixes with ambient flow flowing upwardly into the main cove from a lowermost surface of the airfoil at an entrainment point located aft of the ejection port before passing out of the main cove and into ambient flow passing over an upper surface of the trailing edge device.
2. The system of claim 1 , wherein:
the air ejector is configured to discharge the air jet when the trailing edge device is deployed.
3. The system of claim 1 , wherein:
the ejection port is configured to discharge the air jet in at least one of an upward direction relative to a chord line of the airfoil of an aircraft and an outboard direction relative to a longitudinal axis of the aircraft.
4. The system of claim 1 , wherein:
the airfoil is a wing having a rear spar; and
the ejection port being mounted to the rear spar.
5. The system of claim 1 , wherein:
the air ejector is configured as a fluidic oscillator; and
the fluidic oscillator discharging an air jet in a manner causing the air jet to laterally sweep back-and-forth along a spanwise portion of the trailing edge device.
6. The system of claim 1 , wherein:
the air ejector comprises a plurality of air ejectors.
7. The system of claim 6 , wherein:
the plurality of air ejectors are arranged in a spanwise array.
8. The system of claim 6 , wherein:
the plurality of air ejectors are arranged in clusters.
9. The system of claim 6 , wherein:
the plurality of air ejectors are arranged in two or more rows.
10. The system of claim 1 , wherein:
the trailing edge device is one of a flap, a flaperon, an aileron, and an elevon.
11. The system of claim 1 , wherein:
the trailing edge device is a multi-slotted flap.
12. The system of claim 1 , wherein:
the air ejector is configured as one of a zero-net-mass-flux jet and a pneumatic air ejector.
13. A drag reduction system for a wing, comprising:
an air ejector having an ejection port mounted on or extending aftwardly from a rear spar of the wing, the ejection port terminating within a main cove having side boundaries defined by the rear spar and a forward portion of a flap and an upper boundary defined by an overhang extending from the rear spar, the election port terminating at a location below the overhang; and
the air ejector is configured to discharge an air jet from the ejection port in such a manner that the air jet is discharged into the main cove and mixes with ambient flow flowing upwardly into the main cove from a lowermost surface of the wing at an entrainment point located aft of the ejection port when the flap is deployed before passing out of the main cove and into ambient flow passing over an upper surface of the flap.
14. A method of reducing aerodynamic drag of an airfoil, comprising:
discharging an air jet from an ejection port of an air ejector, the ejection port being mounted on or extending aftwardly from an aft portion of an airfoil main element of the airfoil, the ejection port terminating within a main cove having side boundaries defined by the aft portion of the airfoil main element and a forward portion of a trailing edge device and an upper boundary defined by an overhang extending from the aft portion of the airfoil main element, the ejection port terminating at a location below the overhang; and
directing the air jet from the ejection port into the main cove in such a manner to cause the air jet to mix with ambient flow flowing upwardly into the main cove from a lowermost surface of the airfoil at an entrainment point located aft of the ejection port before passing out of the main cove and into ambient flow passing over an upper surface of the trailing edge device.
15. The method of claim 14 , wherein the step of discharging the air jet includes:
at least partially deploying the trailing edge device; and
discharging the air jet when the trailing edge device is at least partially deployed.
16. The method of claim 14 , wherein the step of discharging the air jet includes:
discharging the air jet in at least one of an upward direction relative to a chord line of the airfoil of an aircraft and an outboard direction relative to a longitudinal axis of the aircraft.
17. The method of claim 14 , wherein the step of discharging the air jet includes:
laterally sweeping the air jet in a back-and-forth manner along a spanwise portion of the trailing edge device.
18. The method of claim 14 , wherein:
the air ejector comprises a plurality of air ejectors.
19. The method of claim 18 , wherein:
the plurality of air ejectors are arranged in clusters of air ejectors.
20. The method of claim 18 , wherein:
the plurality of air ejectors are arranged in two or more rows extending along a spanwise direction.