Circulation control wing: Difference between revisions

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{{short description|Aircraft high-lift device}}

A '''circulation control wing''' (CCW) is a form of [[high-lift device]] for use on the main wing of an aircraft to increase the [[lift coefficient]]. CCW technology has been in the research and development phase for over sixty years, and the early models were called [[blown flaps]].<ref>{{cite web |url=http://www.sae.org/technical/papers/2005-01-3192 |title=Circulation Control Wing |accessdate=2007-12-15}}</ref>

A '''circulation control wing''' (CCW) is a form of [[high-lift device]] for use on the main wing of an aircraft to increase the maximum [[lift coefficient]] and reduce the [[stalling speed]]. CCW technology has been in the research and development phase for over sixty years,. and[[Blown theflaps]] earlywere modelsan wereearly calledexample [[blownof flaps]]CCW.<ref name="Circulation Control Wing">{{cite web |url=http://www.sae.org/technical/papers/2005-01-3192 |title= A Propulsion Concept for Circulation Control Wing Technology |accessdate=20072024-1207-1527 |archive-url=https://web.archive.org/web/20080102083136/http://www.sae.org/technical/papers/2005-01-3192 |archive-date=2008-01-02 |url-status=dead |publisher=[[SAE International]]}}</ref>

The CCW works by increasing the velocity of the airflow over the [[leading edge]] and [[trailing edge]] of a specially designed aircraft [[wing]] using a series of blowing slots that eject high pressure jet air. The wing has a rounded trailing edge to tangentially eject the air through the [[Coanda]] effect thus causing lift.<ref>{{cite web |url=http://pdf.aiaa.org/preview/CDReadyMFLC06_1187/PV2006_3011.pdf |title=Large Eddy Simulation of a Circulation Control Airfoil. |accessdate=2007-12-18 |last=Slomski |first=J.F. |coauthors= |date=2006-06-05|format=PDF}}</ref> The increase in [[velocity]] of the airflow over the wing also adds to the lift force through conventional [[airfoil]] lift production.<ref name="cc">{{cite book |title=FlightWise |last=Carpenter |first=Chris |year=1996 |publisher=Airlife Publishing Ltd |___location= UK |}}</ref>

The CCW works by increasing the velocity of the airflow over the [[leading edge]] and [[trailing edge]] of a specially designed aircraft [[wing]] using a series of blowing slots that eject highjets pressureof jethigh-pressure air. The wing has a rounded trailing edge to tangentially eject the air through the [[CoandaCoandă effect]] effect thus causing lift.<ref name="Slomski">{{cite webbook |url=httphttps://pdfarc.aiaa.org/previewdoi/CDReadyMFLC06_1187abs/PV2006_301110.pdf2514/6.2006-3011 |title=Large Eddy Simulation of a Circulation Control Airfoil. |accessdate=20072024-1207-1827 |last=Slomski |first=J.F. |coauthors= |date=2006-06-05 |formatpublisher=[[American Institute of Aeronautics and Astronautics]] |doi=10.2514/6.2006-3011 |isbn=978-1-62410-036-9 |url-access=PDFsubscription}}</ref> The increase in [[velocity]] of the airflow over the wing also adds to the lift force through conventional [[airfoil]] lift production.<ref name="cc">{{cite book |title=FlightWise: Principles of Aircraft Flight |url=https://archive.org/details/flightwiseprinci0000carp |url-access=registration |last=Carpenter |first=Chris |year=1996 |publisher=Airlife Publishing Ltd |___location= UK |isbn=9781853107191 }}</ref>

[[Image:Circulation Control Airfoil.svg|thumb|The [[trailing edge]] of a CCW showing the blowing slot and tangential [[coanda]] airflow.]]

== Purpose ==

The main purpose of the circulation control wing is to increase the [[lifting force]] of an aircraft at times when large lifting forces at slowlow speeds are required, such as [[takeoff]] and [[landing]]. Wing [[Flap (aircraft)|flaps]] and [[Leading edge slats|slats]] are currently used during landing on almost all aircraft and on takeoff by larger jets. While flaps and slats are effective in increasing lift, they do so at a high cost of drag.<ref name="cc" /> The benefit of the circulation control wing is that no extra drag is created and the lift coefficient is greatly increased. It is being claimed that such a system could increase the landingmaximum coefficient of lift in the landing configuration of a [[Boeing 737]] by 150% to 250%, thus reducing approach speeds by 35% to 45% and landing distances by 55% to 75% and that; such advances in wing design could allow for a dramatic wingreduction in the size reductionof inthe large,wing wideof bodya jetslarge jet airplane.<ref name="cc" />

The main purpose of the circulation control wing is to increase the [[lifting force]] of an aircraft at times when large lifting forces at slow speeds are required, such as [[takeoff]] and [[landing]]. Wing [[Flap (aircraft)|flaps]] and [[Leading edge slats|slats]] are currently used during landing on almost all aircraft and on takeoff by larger jets. While flaps and slats are effective in increasing lift, they do so at a high cost of drag.<ref name="cc" /> The benefit of the circulation control wing is that no extra drag is created and the lift coefficient is greatly increased. It is being claimed that such a system could increase the landing coefficient of lift of a [[Boeing 737]] by 150% to 250%, thus reducing approach speeds by 35% to 45% and landing distances by 55% to 75% and that such advances in wing design could allow for dramatic wing size reduction in large, wide body jets.<ref name="cc" />

[[Image:CCW Diagram.jpg|thumb|A [[Blackburn Buccaneer|Buccaneer]] pictured with the blowing slots visible on the leading edges. The extended [[Flap (aircraft)|flaps]] are contributing to the [[coanda]] airflow over the wing.]]

== Other uses ==

===== Increased maneuverability =====

At low speeds, an aircraft has reduced airflow over the [[wing]] and [[vertical stabilizer]]. This causes the [[Flight control surfaces|control surfaces]] ([[ailerons]], [[elevatorselevator (aircraft)|elevator]]s and [[rudder]]) to be less effective. The CCW system increases the airflow over these surfaces and consequently can allow much higher maneuverability at low speeds.<ref name="Circulation Control Technology">{{cite web |author=Wright, Tim |url=http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|archive-url=https://archive.today/20120716165638/http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|url-status=dead|archive-date=2012-07-16 |title=CirculationThat ControlExtra Little Lift Technology|accessdate=20072024-1207-1527 |publisher=[[Air & Space]] magazine}}</ref> However, if one of the CCW systems should fail at low speed, the affected wing is likely to [[stall (flight)|stall]] which could result in an inescapable [[spin (flight)|spin]]. Finally, the CCW system could be used on multi-engine aircraft in the result of an engine failure to cancel the [[asymmetric forces]] from the loss of power on one wing.<ref>{{cite web |url=http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|titlename="Circulation Control Technology|accessdate=2007-12-15}}<"/ref>

===== Noise reduction =====

At low speeds, an aircraft has reduced airflow over the [[wing]] and [[vertical stabilizer]]. This causes the [[control surfaces]] ([[ailerons]], [[elevators]] and [[rudder]]) to be less effective. The CCW system increases the airflow over these surfaces and consequently can allow much higher maneuverability at low speeds.<ref>{{cite web |url=http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|title=Circulation Control Technology|accessdate=2007-12-15}}</ref> However, if one of the CCW systems should fail at low speed, the affected wing is likely to [[stall (flight)|stall]] which could result in an inescapable [[spin (flight)|spin]]. Finally, the CCW system could be used on multi-engine aircraft in the result of an engine failure to cancel the [[asymmetric forces]] from the loss of power on one wing.<ref>{{cite web |url=http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|title=Circulation Control Technology|accessdate=2007-12-15}}</ref>

The use of a CCW system eliminates the need for large complex components in the free stream such as [[Flap (aircraft)|flaps]] and [[Leading edge slats|slats]], greatly reducing the [[noise pollution]] of modern aircraft.<ref>{{cite web |url=http://pdf.aiaa.org/preview/CDReadyMFLC06_1187/PV2006_3011.pdf |title=Large Eddy Simulation of a Circulation Control Airfoil. |accessdate=2007-12-18 |lastname="Slomski |first=J.F. |coauthors= |date=2006-06-05|format=PDF}}<"/ref> Additionally, a much shorter ground roll coupled with steeper climb outs and approaches reduces the ground noise footprint. The blowing slots themselves will contribute very little to the noise of the aircraft as each slot is just a fraction of an inch wide.<ref>{{cite web |url=http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|titlename="Circulation Control Technology|accessdate=2007-12-15}}<"/ref>

===== Noise reduction =====

The use of a CCW system eliminates the need for large complex components in the free stream such as [[Flap (aircraft)|flaps]] and [[Leading edge slats|slats]], greatly reducing the [[noise pollution]] of modern aircraft.<ref>{{cite web |url=http://pdf.aiaa.org/preview/CDReadyMFLC06_1187/PV2006_3011.pdf |title=Large Eddy Simulation of a Circulation Control Airfoil. |accessdate=2007-12-18 |last=Slomski |first=J.F. |coauthors= |date=2006-06-05|format=PDF}}</ref> Additionally, a much shorter ground roll coupled with steeper climb outs and approaches reduces the ground noise footprint. The blowing slots themselves will contribute very little to the noise of the aircraft as each slot is just a fraction of an inch wide.<ref>{{cite web |url=http://www.airspacemag.com/issues/2007/april-may/custer_channel_wing.php?page=2|title=Circulation Control Technology|accessdate=2007-12-15}}</ref>

== Powering the wing ==

The main problem with the circulation control wing is the need for high energy air to be blown over the wing's surface. Such air is often taken[[Bleed air|bled from the engine]]; however, this drastically reduces engine power production and consequently defiescounteracts the purpose of the wing. Other options are taking the exhaust gases (which must first be cooled) or using multiple, lightweight gas generators, which are separate from the main aircraft engines.<ref>{{cite web |url=http://www.sae.org/technical/papers/2005-01-3192 |titlename="Circulation Control Wing |accessdate=2007-12-15}}<"/ref>

The main problem with the circulation control wing is the need for high energy air to be blown over the wing's surface. Such air is often taken from the engine however this drastically reduces engine power production and consequently defies the purpose of the wing. Other options are taking the exhaust gases (which must first be cooled) or using multiple, lightweight gas generators, which are separate from the main aircraft engines.<ref>{{cite web |url=http://www.sae.org/technical/papers/2005-01-3192 |title=Circulation Control Wing |accessdate=2007-12-15}}</ref>

==References==

<references />

==See also==

Line 33 ⟶ 26:

*[[Flap (aircraft)]]

*[[High-lift device]]

*[[Coanda effect]]

*[[Blown flaps]]

==References==

[[Category:Aerodynamics]]

{{reflist}}

[[Category:Wing design]]

[[Category:Aircraft components]]

[[Category:WingAircraft wing design]]

[[Category:Aircraft wing components]]