# US 7,744,039 B2 · Systems and methods for controlling flows with electrical pulses

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- Number: US 7,744,039 B2
- Document ID: US7744039B2
- Status: Granted
- Kind: B2
- Application number: 11/649,706
- Filed: 2007-01-03
- Published: 2008-01-31
- Granted: 2010-06-29
- Earliest claimed: 2006-01-03
- Assignees: The Boeing Company; Princeton University
- Inventors: Richard B. Miles; Sergey O. Macheret; Mikhail Shneider; Alexandre Likhanskii; Joseph Steven Silkey
- Web page: https://patentgrep.com/patent/US7744039B2

## CPC

- B64C 23/005: {by other means not covered by groups B64C23/02 - B64C23/08, e.g. by electric charges, magnetic panels, piezoelectric elements, static charges or ultrasounds}
- B64D 15/12: by electric heating (heating arrangements specially adapted for transparent or reflecting areas H05B3/84)
- F15D 1/12: by influencing the boundary layer
- H05H 1/2439: {Surface discharges, e.g. air flow control}
- B64C 2039/105: {of blended wing body type}
- B64C 2230/12: by using electromagnetic tiles, fluid ionizers, static charges or plasma
- F05D 2270/172: by a plasma generator, e.g. control of ignition
- Y02T 50/10: Drag reduction
- B64C: AEROPLANES; HELICOPTERS
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- F15D: FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Systems and methods for controlling flow with electrical pulses are disclosed. An aircraft system in accordance with one embodiment includes an aerodynamic body having a flow surface exposed to an adjacent air stream, and a flow control assembly that includes a first electrode positioned at least proximate to the flow surface and a second electrode positioned proximate to and spaced apart from the first electrode. A dielectric material can be positioned between the first and second electrodes, and a controller can be coupled to at least one of the electrodes, with the controller programmed with instructions to direct air-ionizing pulses to the electrode, and provide a generally steady-state signal to the electrode during intervals between the pulses.

## Claims

### Claim 1

An aircraft system, comprising:
an aerodynamic body having a flow surface exposed to an adjacent airstream; and
a flow control assembly that includes:
a first electrode positioned at least proximate to the flow surface;
a second electrode positioned proximate to and spaced apart from the first electrode;
a dielectric material between the first and second electrodes; and
a controller coupled to at least one of the first and second electrodes, the controller being programmed with instructions to direct air-ionizing pulses to the at least one electrode, and apply a non-ionizing generally steady-state bias voltage signal to the at least one electrode during intervals between the pulses.

### Claim 2 (depends on 1)

The system of claim 1 wherein the first electrode is exposed to the adjacent airstream and wherein the dielectric material is positioned between the second electrode and the adjacent airstream.

### Claim 3 (depends on 1)

The system of claim 1 wherein the first electrode, the second electrode and the dielectric material form at least a portion of a plasma actuator, and wherein the flow control assembly includes multiple plasma actuators spaced apart from each other along the flow surface.

### Claim 4 (depends on 1)

The system of claim 1 wherein the flow control assembly is configured to accelerate an adjacent airflow to at least 100 m/s, and wherein a power consumption of the plasma actuator assembly is at least ten times less than that of a plasma actuator assembly having a controller that delivers symmetric, biphasic pulses producing the same airflow velocity.

### Claim 5 (depends on 1)

The system of claim 1 wherein the aerodynamic body includes an aircraft airfoil, and wherein the flow surface includes an external surface of the airfoil.

### Claim 6 (depends on 5)

The system of claim 5 wherein the first electrode, the second electrode and the dielectric material form at least a portion of a plasma actuator, and wherein the plasma actuator is the only plasma actuator carried by the airfoil along a generally streamwise line that intersects the plasma actuator.

### Claim 7 (depends on 6)

The system of claim 6 wherein the plasma actuator is positioned at least proximate to a leading edge of the airfoil.

### Claim 8 (depends on 5)

The system of claim 5 wherein the first electrode, the second electrode and the dielectric material form at least a portion of a plasma actuator, and wherein the plasma actuator is one of only two plasma actuators carried by the airfoil along a generally streamwise line that intersects the two plasma actuators.

### Claim 9 (depends on 1)

The system of claim 1 wherein the aerodynamic body includes an airbreathing engine, and wherein the flow surface includes an air inlet flow surface positioned to provide airflow to the engine via an air inlet aperture.

### Claim 10 (depends on 9)

The system of claim 9 wherein the flow surface is positioned forward of the inlet aperture to direct flow into the inlet aperture.

### Claim 11 (depends on 9)

The system of claim 9 wherein the first electrode, the second electrode and the dielectric material form at least a portion of a plasma actuator, and wherein the system includes multiple plasma actuators spaced apart from each other along the flow surface.

### Claim 12 (depends on 9)

The system of claim 9 wherein the flow surface includes no more than five rows of plasma actuators positioned forward of and generally transverse to the inlet aperture.

### Claim 13 (depends on 12)

The system of claim 12 wherein each row of plasma actuators includes multiple plasma actuators.

### Claim 14 (depends on 13)

The system of claim 13 wherein each row of actuators includes two actuators arranged in a chevron shape.

### Claim 15 (depends on 1)

The system of claim 1 wherein the first electrode includes at least one of a conductive and a semiconductive protective coating.

### Claim 16 (depends on 15)

The system of claim 15 wherein the protective coating includes silicon and a dopant.

### Claim 17 (depends on 15)

The system of claim 15 wherein the first electrode includes a conductive coating comprising at least one of tungsten and nichrome.

### Claim 18

A plasma actuator system, comprising:
a first electrode;
a second electrode positioned proximate to and spaced apart from the first electrode;
a dielectric material between the first and second electrodes; and
a controller coupled to at least one of the first and second electrodes, the controller being programmed with instructions to direct air-ionizing pulses to the at least one electrode, and apply a non-ionizing generally steady-state bias voltage signal to the at least one electrode during intervals between the pulses.

### Claim 19 (depends on 18)

The system of claim 18, further comprising an aircraft having a flow surface exposed to an adjacent fluid flow field, and wherein the at least one electrode is positioned at least proximate to the flow surface.

### Claim 20 (depends on 19)

The system of claim 19 wherein the flow surface includes an external surface of an airfoil.

### Claim 21 (depends on 20)

The system of claim 20 wherein the first electrode, the second electrode and the dielectric material form at least a portion of a plasma actuator, and wherein the plasma actuator is the only plasma actuator carried by the airfoil along a generally streamwise line that intersects the plasma actuator.

### Claim 22 (depends on 19)

The system of claim 19 wherein the flow surface includes an air inlet flow surface positioned to provide air to an airbreathing aircraft engine via an inlet aperture.

### Claim 23 (depends on 22)

The system of claim 22 wherein the first electrode, the second electrode and the dielectric material form at least a portion of a plasma actuator, and wherein the system includes multiple plasma actuators spaced apart from each other along the flow surface, the flow surface including no more than five rows of plasma actuators positioned forward of and generally transverse to the inlet aperture, with each row of actuators including at least two actuators arranged in a chevron shape.

### Claim 24 (depends on 18)

The system of claim 18 wherein the controller is programmed with instructions to direct pulses having a pulse width of about 100 nanoseconds or less.

### Claim 25 (depends on 18)

The system of claim 18 wherein the controller is programmed with instructions to direct pulses having a pulse width of from about two nanoseconds to about ten nanoseconds.

### Claim 26 (depends on 18)

The system of claim 18 wherein the controller is programmed with instructions to direct pulses at a negative potential and apply a generally steady-state signal at a positive potential.

### Claim 27 (depends on 18)

The system of claim 18 wherein the controller is programmed with instructions to direct pulses with an interpulse interval of from about one to about two microseconds.

### Claim 28 (depends on 18)

The system of claim 18 wherein the air-ionizing pulses and the generally steady-state signal form portions of a first waveform, and wherein the controller is programmed with instructions to direct signals with a second waveform different than the first waveform to protect a surface at least proximate to the electrodes from ice formation.

### Claim 29 (depends on 18)

The system of claim 18 wherein the controller is programmed with instructions to direct pulses having a voltage amplitude greater than a voltage amplitude of the generally steady-state signal.

### Claim 30 (depends on 18)

The system of claim 18 wherein the first electrode includes at least one of a conductive and a semiconductive protective coating.