Share
VIDEOS 1 TO 50
BLEED AIR explained
BLEED AIR explained
Published: 2015/10/08
Channel: Tim van Beveren
737NGX Training- Bleed Air
737NGX Training- Bleed Air
Published: 2012/05/07
Channel: Angle of Attack
Bleed Air : Turbine Engines - A Closer Look
Bleed Air : Turbine Engines - A Closer Look
Published: 2013/11/30
Channel: AgentJayZ
Bleed Air
Bleed Air
Published: 2016/10/02
Channel: Aviation English.club
What is BLEED AIR? What does BLEED AIR mean? BLEED AIR meaning, definition & explanation
What is BLEED AIR? What does BLEED AIR mean? BLEED AIR meaning, definition & explanation
Published: 2016/12/04
Channel: The Audiopedia
Combustion  Turbine - Bleed Air
Combustion Turbine - Bleed Air
Published: 2016/01/14
Channel: NDT Welding
How to Bleed Air Out of Your Car
How to Bleed Air Out of Your Car's Cooling System - DIY Method
Published: 2015/10/24
Channel: Ratchets And Wrenches
How to Bleed Air Out of Your Cars Cooling System
How to Bleed Air Out of Your Cars Cooling System
Published: 2014/11/13
Channel: DIY Auto Repair Videos
How To Bleed A Cooling System - EricTheCarGuy
How To Bleed A Cooling System - EricTheCarGuy
Published: 2009/10/28
Channel: EricTheCarGuy
Aerotoxic syndrome: Toxic cabin air caused by bleed-air system could make you sick - TomoNews
Aerotoxic syndrome: Toxic cabin air caused by bleed-air system could make you sick - TomoNews
Published: 2017/08/21
Channel: TomoNews US
contaminated engine bleed air explained 1024x576
contaminated engine bleed air explained 1024x576
Published: 2014/06/23
Channel: Aerotoxic Association
How To Bleed Air Out Of Your Car
How To Bleed Air Out Of Your Car's Brake System.
Published: 2008/08/25
Channel: Scotty Kilmer
Boeing B747-400F CBT #51 Bleed Air System
Boeing B747-400F CBT #51 Bleed Air System
Published: 2016/12/22
Channel: AviationKnowledge
How to do a Complete Brake Flush and Bleed
How to do a Complete Brake Flush and Bleed
Published: 2014/07/29
Channel: ChrisFix
FSLabs A320-X Basics: Bleed Air and Pressurization
FSLabs A320-X Basics: Bleed Air and Pressurization
Published: 2017/07/13
Channel: Blackbox711
How to Bleed or Purge the Air from Disc Brakes System
How to Bleed or Purge the Air from Disc Brakes System
Published: 2011/06/29
Channel: 1A Auto Parts
How to Properly Bleed Engine Cooling System
How to Properly Bleed Engine Cooling System
Published: 2016/05/16
Channel: 1A Auto Parts
How To Bleed Air Out Of A Volkswagen Cooling System
How To Bleed Air Out Of A Volkswagen Cooling System
Published: 2015/05/28
Channel: JamieJones TheCarMan
How to Bleed Plumbing Pipes : Plumbing Plans & Problems
How to Bleed Plumbing Pipes : Plumbing Plans & Problems
Published: 2014/01/25
Channel: ehowathomechannel
How to Bleed your Brakes by Yourself
How to Bleed your Brakes by Yourself
Published: 2017/03/01
Channel: 1A Auto Parts
Hydraulic System - Bleed Air
Hydraulic System - Bleed Air
Published: 2016/02/02
Channel: Total Secure
How to change fuel filters and bleed air in a Yanmar marine diesel
How to change fuel filters and bleed air in a Yanmar marine diesel
Published: 2017/06/28
Channel: spelunkerd
How to bleed your clutch by yourself without fancy tools
How to bleed your clutch by yourself without fancy tools
Published: 2016/08/03
Channel: Protege Garage
How to Bleed A BMW Coolant System
How to Bleed A BMW Coolant System
Published: 2016/07/19
Channel: E36 Fanatics
How to bleed air from hydraulic clutch
How to bleed air from hydraulic clutch
Published: 2015/09/27
Channel: BombChane11
Holley Air Bleed System
Holley Air Bleed System
Published: 2011/03/04
Channel: HolleyPerformance
Car Overheating? How to Bleed Air Out of ANY Car
Car Overheating? How to Bleed Air Out of ANY Car's Cooling System -Flushing Radiator - SOLVED!
Published: 2017/07/25
Channel: pauliojrdiy
How to bleed Power Steering System the RIGHT WAY! Bleed Powersteering
How to bleed Power Steering System the RIGHT WAY! Bleed Powersteering
Published: 2016/03/04
Channel: World Mechanics
How to Bleed Disc Brakes
How to Bleed Disc Brakes
Published: 2012/05/12
Channel: Car and Driver Magazine
How to get air out of brake system (bleed fluid)
How to get air out of brake system (bleed fluid)
Published: 2014/06/04
Channel: Igor Kadulenkov
How to check coolant and Bleed air from Radiator and Engine M3 M5 E36 e38 e39 e46 e53 e90 e60
How to check coolant and Bleed air from Radiator and Engine M3 M5 E36 e38 e39 e46 e53 e90 e60
Published: 2016/01/03
Channel: Nathan's DIY Garage
How To Easily Bleed A Radiator
How To Easily Bleed A Radiator
Published: 2015/04/20
Channel: Silverline ToolsTV
How To Air Bleed Engine Cooling System - Prevent engine Overheating
How To Air Bleed Engine Cooling System - Prevent engine Overheating
Published: 2015/03/05
Channel: StevexNYCperformance
How to Bleed Air After Coolant Replacement Honda Accord
How to Bleed Air After Coolant Replacement Honda Accord
Published: 2012/12/19
Channel: corgLLC
RLR Tip on How To Bleed Air Out Of Your Forks
RLR Tip on How To Bleed Air Out Of Your Forks
Published: 2015/06/09
Channel: Rich Lafferty Racing
The final bleed - how to completely purge/bleed the air and refill your jack
The final bleed - how to completely purge/bleed the air and refill your jack
Published: 2016/10/07
Channel: WJ Handy Dad
How To Bleed Air Out Of The Oil Line On a Boiler Burner
How To Bleed Air Out Of The Oil Line On a Boiler Burner
Published: 2013/10/30
Channel: HomeOwnerRepair
How to bleed brakes using the " One person " method
How to bleed brakes using the " One person " method
Published: 2011/09/20
Channel: backyardmech
737 Sistema Neumático. Bleed Air System (1)
737 Sistema Neumático. Bleed Air System (1)
Published: 2017/04/30
Channel: Luis Valtueña
How to Bleed Motorcycle Brakes by J&P Cycles
How to Bleed Motorcycle Brakes by J&P Cycles
Published: 2014/06/19
Channel: J&P Cycles
Nissan V6 Radiator Bleed Air - Video 2 - 2004 Quest
Nissan V6 Radiator Bleed Air - Video 2 - 2004 Quest
Published: 2017/02/28
Channel: dial2fast
How to bleed air from a radiator. Get more heat from your radiators.
How to bleed air from a radiator. Get more heat from your radiators.
Published: 2012/10/29
Channel: dereton33
Bleed Air from the Pneumatic System
Bleed Air from the Pneumatic System
Published: 2016/07/18
Channel: Aviation Interactive Learning Society
How to Bleed the Cooling System on Dodge Charger, Dodge Magnum, Chrysler 300
How to Bleed the Cooling System on Dodge Charger, Dodge Magnum, Chrysler 300
Published: 2016/06/04
Channel: World Mechanics
Bleed Brake Master Cylinder  While On Car WITHOUT Bench Bleeding Done Alone-No Partner!
Bleed Brake Master Cylinder While On Car WITHOUT Bench Bleeding Done Alone-No Partner!
Published: 2016/10/16
Channel: artbyrobot
6.4 Powerstroke Air/ Fuel Bleed Tool
6.4 Powerstroke Air/ Fuel Bleed Tool
Published: 2011/07/17
Channel: DieselTechRon
How to bleed air from a ford f150 cooling system, heater core
How to bleed air from a ford f150 cooling system, heater core
Published: 2017/03/17
Channel: Kenny Pin
How To Bleed The Air Out of The Hydraulic System on a Load Trail Gravity Tilt Deck Trailer
How To Bleed The Air Out of The Hydraulic System on a Load Trail Gravity Tilt Deck Trailer
Published: 2015/05/22
Channel: LoadTrailMfg
How To Bleed Trapped Air From Baseboard Heater
How To Bleed Trapped Air From Baseboard Heater
Published: 2016/02/27
Channel: HomeOwnerRepair
How to Bleed a Hot Water Heating System - Boiler, Hydronic Heating System
How to Bleed a Hot Water Heating System - Boiler, Hydronic Heating System
Published: 2017/02/13
Channel: Andrew W
NEXT
GO TO RESULTS [51 .. 100]

WIKIPEDIA ARTICLE

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Bleed air produced by gas turbine engines is compressed air that is taken from the compressor stage of those engines, which is upstream of the fuel-burning sections. In modern airliner engines, two regulator valves (high stage and low stage) turn on and off automatically and are controlled by at least "...two air supply and cabin pressure controllers (ASCPCs) which open and close appropriate valves. Engine bleed air comes from the high stage or low stage engine compressor section. Low stage air is used during high power setting operation, and high stage air is used during descent and other low power setting operations."[1][2] Bleed air from that system can be utilized for internal cooling of the engine, cross-starting another engine, engine and airframe anti-icing, cabin pressurization, pneumatic actuators, air-driven motors, pressurizing the hydraulic reservoir, and waste and water storage tanks. Some engine maintenance manuals refer to such systems as "customer bleed air".[3][4][5] Bleed air is valuable in an aircraft for two properties: high temperature and high pressure (typical values are 200–250 °C and 275 kPa (40 PSI), for regulated bleed air exiting the engine pylon for use throughout the aircraft).

Uses[edit]

Cabin pressure and bleed air controls in a Boeing 737-800

In civil aircraft, bleed air's primary use is to provide pressure for the aircraft cabin by supplying air to the environmental control system. Additionally, bleed air is used to keep critical parts of the plane (such as the wing leading edges) ice-free.[6]

Bleed air is used on many aircraft systems because it is easily available, reliable, and a potent source of power. For example, bleed air from an airplane engine is used to start the remaining engines. Lavatory water storage tanks are pressurized by bleed air that is fed through a pressure regulator.[6]

When used for cabin pressurization, the bleed air from the engine must first be cooled (as it exits the compressor stage at temperatures as high as 250 °C) by passing it through an air-to-air heat exchanger cooled by cold outside air. It is then fed to an air cycle machine unit that regulates the temperature and flow of air into the cabin, keeping the environment comfortable.[6]

Bleed air is also used to heat the engine intakes. This prevents ice from forming, accumulating, breaking loose, and being ingested by the engine, possibly damaging it.[7]

On aircraft powered by jet engines, a similar system is used for wing anti-icing by the 'hot-wing' method. In icing conditions, water droplets condensing on a wing's leading edge can freeze. If that happens, the ice build-up adds weight and changes the shape of the wing, causing a degradation in performance, and possibly a critical loss of control or lift. To prevent this, hot bleed air is pumped through the inside of the wing's leading edge, heating it to a temperature above freezing, which prevents the formation of ice. The air then exits through small holes in the wing edge.

On propeller-driven aircraft, it is common to use bleed air to inflate a rubber boot on the leading edge, breaking the ice loose after it has already formed.[6][7]

Bleed air from the high-pressure compressor of the engine is used to supply reaction control valves as used for part of the flight control system in the Harrier jump jet family of military aircraft.[8]

Contamination[edit]

On rare occasions, bleed air used for air-conditioning, and pressurization can be contaminated by chemicals such as oil or hydraulic fluid.[9] This is known as a fume event. While those chemicals can be irritating, such rare events have not been established to cause long term harm.[10][11]

Certain neurological and respiratory ill health effects have been linked anecdotally to exposure to bleed air that has been alleged to have been contaminated with toxic levels on commercial and military aircraft. This alleged long-term illness is referred to as Aerotoxic Syndrome by agenda groups, but it is not a medically recognized syndrome. One alleged potential contaminant is tricresyl phosphate.

Many lobbying groups have been set up to advocate for research into this alleged hazard. The groups include the Aviation Organophosphate Information Site (AOPIS) (2001), the Global Cabin Air Quality Executive (2006) and the UK-based Aerotoxic Association (2007). Cabin Environment Research is one of many functions of the ACER Group,[12] but their researchers have not yet established any causal relationship relationship.[13][14]

Although a study made for the EU in 2014 confirmed that contamination of cabin air could be a problem, that study also stated:

"A lot of reported fume events caused comfort limitations for the occupants but posed no danger. A verification of cabin air contamination with toxic substances (e.g. TCP/TOCP) was not possible with the fume events the BFU investigated."[15]

In spite of the fact that no science evidence to date has ever found that airliner cabin air has been contaminated to toxic levels (exceeding known safe levels, in ppm, of any dangerous chemical), a court in Australia, In March 2010, found in favor of a former airline flight attendant who claimed she suffered chronic respiratory problems after being exposed to oil fumes on a trip in March 1992, even though she was able to continue working as a flight attendant and in other jobs for over 10 years after that alleged exposure in 1991.[16]

Bleedless aircraft[edit]

Bleed air systems have been in use for several decades in passenger jets. Recent improvements in solid-state electronics have enabled pneumatic power systems to be replaced by electric power systems. In a bleedless aircraft such as the Boeing 787, each engine has two variable-frequency electrical generators to compensate for not providing compressed air to external systems. Eliminating bleed air and replacing it with extra electric generation is believed to provide a net improvement in engine efficiency, lower weight, and ease of maintenance.[17]

Benefits[edit]

A bleedless aircraft achieves fuel efficiency by eliminating the process of compressing and decompressing air, and by reducing the aircraft's mass due to the removal of ducts, valves, heat exchangers, and other heavy equipment.[18]

The APU (auxiliary power unit) does not need to supply bleed air when the main engines are not operating. Aerodynamics are improved due to the lack of bleed air vent holes on the wings. By driving cabin air supply compressors at the minimum required speed, no energy wasting modulating valves are required. High-temperature, high-pressure air cycle machine (ACM) packs can be replaced with low temperature, low-pressure packs to increase efficiency. At cruise altitude, where most aircraft spend the majority of their time and burn the majority of their fuel, the ACM packs can be bypassed entirely, saving even more energy. Since no bleed air is taken from the engines for the cabin, the potential of engine oil contamination of the cabin air supply is eliminated.[18]

Lastly, advocates of the design say it improves safety as heated air is confined to the engine pod, as opposed to being pumped through pipes and heat exchangers in the wing and near the cabin, where a leak could damage surrounding systems.[18]

Tradeoffs[edit]

In the 787, cabin air enters from under the fuselage and is compressed as required. De-icing is achieved by electro-thermal heating elements embedded in the wing's leading edge. Hydraulic pumps for flaps, slats, speed brakes and other control surfaces are also powered electrically.

Eliminating bleed air increases the electric load, as cabin pressurization, anti-ice/de-ice systems, and other functions need to be powered electrically instead. This necessitates an increased size of electrical generators as well as higher-power power distribution boards and more sophisticated backup and control systems.

See also[edit]

References[edit]

  1. ^ "777 Bleed Air". 
  2. ^ "Global 300 Bleed Air" (PDF). 
  3. ^ "Naval Operations Manual". 
  4. ^ "European Space Agency" (PDF). 
  5. ^ "mil-spec". 
  6. ^ a b c d "Bleed Air Systems". Skybrary.aero. Retrieved January 1, 2013. 
  7. ^ a b "Ice Protection Systems". Skybrary. Retrieved January 1, 2013. 
  8. ^ "Technical" page on harrier.org.uk website, viewed 2013-11-24
  9. ^ Sarah Nassauer (30 July 2009). "Up in the Air: New Worries About ‘Fume Events’ on Planes". Wall Street Journal. Retrieved 29 December 2012. 
  10. ^ Nassauer, Sarah (July 30, 2009). "Up in the Air: New Worries About 'Fume Events' on Planes". Wall Street Journal. Retrieved December 31, 2012. 
  11. ^ "Skydrol FAQ". Skydrol. Retrieved December 31, 2012. 
  12. ^ "Airliner Cabin Environment Research". 
  13. ^ Bagshaw, Michael (September 2008). "The Aerotoxic Syndrome" (PDF). European Society of Aerospace Medicine. Archived from the original (PDF) on August 27, 2010. Retrieved December 31, 2012. 
  14. ^ Select Committee on Science and Technology (2000). "Chapter 4: Elements Of Healthy Cabin Air". Science and Technology – Fifth Report (Report). House of Lords. Retrieved 2010-07-05. 
  15. ^ "Study of Reported Occurrences in Conjunction with Cabin Air Quality in Transport Aircraft" (PDF). German Federal Bureau of Aircraft Accident Investigation. Retrieved May 2014.  Check date values in: |access-date= (help)
  16. ^ Turner v Eastwest Airlines Limited (2009) at Dust Diseases Tribunal of New South Wales
  17. ^ AERO 787 No Bleed Systems The Boeing Company 2008
  18. ^ a b c Sinnett, Mike (2008). "787 No-Bleed Systems". Boeing. Retrieved January 1, 2013. 

Disclaimer

None of the audio/visual content is hosted on this site. All media is embedded from other sites such as GoogleVideo, Wikipedia, YouTube etc. Therefore, this site has no control over the copyright issues of the streaming media.

All issues concerning copyright violations should be aimed at the sites hosting the material. This site does not host any of the streaming media and the owner has not uploaded any of the material to the video hosting servers. Anyone can find the same content on Google Video or YouTube by themselves.

The owner of this site cannot know which documentaries are in public domain, which has been uploaded to e.g. YouTube by the owner and which has been uploaded without permission. The copyright owner must contact the source if he wants his material off the Internet completely.

Powered by YouTube
Wikipedia content is licensed under the GFDL and (CC) license