Wide chord

Wide chord

A wide chord fan engine is a term to describe a modern turbofan jet engine having a ducted fan with a specific blade geometry - In layman's terms, they would be described as having wider blades than other jet engines.

Overview

The main fan on a jet engine consists of a number of aerofoils mounted at the rotational center on the fandisc, and as the engine core rotates the fanblades accelerate an airmass and create the force to move forward which gives thrust (in accordance with Newton's Third Law).

In theory the larger the fan diameter (the line from the tip of one fanblade to its opposite member) the greater the thrust. In practical applications, fansize is limited by the weight, the space available around the aircraft and by the increased drag (resistance) generated by the larger frontal area.

In the race to achieve better fuel economy, more thrust and less weight & noise from jet engines, designers have refined the blade design and materials to extract more thrust for any given fandisc area. One significant improvement [http://civil.rolls-royce.com/wide-chord-jet-engine-fan-blades Rolls Royce Plc, 2004] is to make blade chords wider and, more recently, alter the blade geometry to give it a scimitar-like shape. Further refinements include making the blades from a light material such as titanium and to manufacture them with a hollow cross-section.

Modern jet engines such as the Rolls Royce Trent 900 engine which powers the Airbus A380 and the Engine Alliance GP7000 are examples of wide chord fan engines.

Key design considerations

The geometry of a jet engine blade is essetially that of an airfoil and as such, there is no single optimum design. As with most mechanical components, the blade is a compromise in trying to achieve as large a blade area as possble within the practical constraints: Widening the blade chord will increase the blade drag while lengthening the blade will increase tip speed (and noise) plus it may make the fandisc impractically large. A larger blade is also heavier, which when taken together with increasing tip speed as the fandisc gets larger, puts a point of diminishing return between weight and blade length (tip speed.) [http://www.aerospaceweb.org/question/propulsion/q0039.shtml Aerospaceweb.org; Jeff Scott, 12 August 2001]

A wide chord engine addresses this by having fewer, wider, blades meaning a wide chord fan engine will have fewer, but more effective, fanblades compared to a regular jet enginge. To address the weight issue, blades are often hollow and made from titanium. Finally, blades are often given a scimitar shape to achieve higher flying speeds [http://www.geae.com/education/vocabulary.html | GE Aviation: Engine Education, 2008] .

References

* [http://www.aerospaceweb.org/question/propulsion/q0039.shtml AerospaceWeb-Propeller Design]
* [http://people.bath.ac.uk/lm224/types%20of%20turbines.htm Types of Turbines, University of Bath, UK]

External links

[http://civil.rolls-royce.com/wide-chord-jet-engine-fan-blades The Rolls Royce wide chord fan blade] [http://civil.rolls-royce.com/Trent-900-jet-aero-engines The Rolls Royce Trent 900 wide chord jet engine]


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Chord (music) — Instruments and voices playing and singing different notes create chords. This article describes pitch simultaneity and harmony in music. For other meanings of the word, see Chord. A chord in music is any harmonic set of two–three or more notes… …   Wikipedia

  • (I'd Go The) Whole Wide World — Infobox Single Name = (I d Go The) Whole Wide World Cover size = Border = Caption = Artist = Wreckless Eric Album = Wreckless Eric B side = Semaphore Signals Released = Start date|1977 [ [http://www.wrecklesseric.com/singles.htm Discography… …   Wikipedia

  • I'm Wide Awake, It's Morning — Infobox Album Name = I m Wide Awake, It s Morning Type = studio Artist = Bright Eyes Released = January 25, 2005 Recorded = February 2004: Presto! Recording Studios Lincoln, Nebraska Genre = Indie folk Length = 45:41 Label = Saddle Creek LBJ 72… …   Wikipedia

  • Rolls-Royce RB211 — The Rolls Royce RB211 is a family of high bypass turbofan engines made by Rolls Royce plc and capable of generating 37,400 to 60,600 pounds force (166 to 270 kilonewtons) thrust. Originally developed for the Lockheed L 1011 (TriStar), it entered… …   Wikipedia

  • Mikoyan-Gurevich MiG-21 variants — MiG 21 This is a list of variants and specifications for variants of the Mikoyan Gurevich MiG 21, which differed considerably between models. Co …   Wikipedia

  • airplane — /air playn /, n. 1. a heavier than air aircraft kept aloft by the upward thrust exerted by the passing air on its fixed wings and driven by propellers, jet propulsion, etc. 2. any similar heavier than air aircraft, as a glider or helicopter. Also …   Universalium

  • Messerschmitt Bf 109 variants — Main article: Messerschmitt Bf 109 Bf 109 Bf 109G 10, with Erla Haube canopy and taller, wooden vertical fin/rudd …   Wikipedia

  • Rolls-Royce Trent — are a family of high bypass turbofan engines manufactured by Rolls Royce. All are developments of the RB211 with thrust ratings of between 53,000 and 95,000 lbf (236 to 423 kN). Versions of the Trent are in service on the Airbus A330, A340, A380… …   Wikipedia

  • Cranwell CLA.4 — CLA.4 The third CLA.4 exhibited after restoration at the Alberta Aviation Museum in Edmonton …   Wikipedia

  • CFM International CFM56 — CFM56 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”