Circulation control wing: Difference between revisions

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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. [[Blown flaps]] were an early example of 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=2024-07-27 |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 jets of high-pressure air. The wing has a rounded trailing edge to tangentially eject the air through the [[Coandă effect]] thus causing lift.<ref name="Slomski">{{cite webbook |url=https://arc.aiaa.org/doi/abs/10.2514/6.2006-3011 |title=Large Eddy Simulation of a Circulation Control Airfoil. |accessdate=2024-07-27 |last=Slomski |first=J.F. |date=2006-06-05 |publisher=[[American Institute of Aeronautics and Astronautics]] |doi=10.2514/6.2006-3011 |isbn=978-1-62410-036-9 |url-access=subscription}}</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.]]

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== 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]], [[elevator (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=That Extra Little Lift |accessdate=2024-07-27 |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 name="Circulation Control Technology"/>

=== Noise reduction ===

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== 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 [[Bleed air|bled from the engine]]; however, this drastically reduces engine power production and consequently counteracts 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 name="Circulation Control Wing"/>

==See also==