A blisk is a single engine component consisting of a rotor disk and blades, which may be either integrally cast, machined from a solid piece of material, or made by welding individual blades to the rotor disk. The term is used mainly in aerospace

Aerospace

Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...

 engine design. The word is a portmanteau of blade and disk, the two components it replaces in turbomachinery

Turbomachinery

Turbomachinery, in mechanical engineering, describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid...

. Blisks may also be known as integrally bladed rotors (IBR).

History

Blisk manufacturing has been used since the mid 1980s. It was first used by Sermatech-Lehr (now known as GKN

GKN

GKN plc is a multinational automotive and aerospace components company headquartered in Redditch, United Kingdom. The company was formerly known as Guest, Keen and Nettlefolds and can trace its origins back to 1759 and the birth of the Industrial Revolution.GKN is listed on the London Stock...

 Aerospace ) in 1985 for the compressors of the T700 helicopter

Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 engine. Since then, its use has continued to increase in major applications for both compressors and fan blade rotors. Examples include the Rocketdyne RS-68 rocket engine and the General Electric F110

General Electric F110

-External links:* - The F110 Engine Family* - F110-GE-100 Gallery* - F110* - General Electric F110...

 turbofan.

The F-35B variant of the Joint Strike Fighter uses blisks to achieve VTOL

VTOL

A vertical take-off and landing aircraft is one that can hover, take off and land vertically. This classification includes fixed-wing aircraft as well as helicopters and other aircraft with powered rotors, such as cyclogyros/cyclocopters and tiltrotors...

.

Engine manufacturer CFM International

CFM International

CFM International is a joint venture between GE Aviation, a division of General Electric of the United States and Snecma, a division of Safran of France...

 is using blisk technology in the compressor section of its Leap-X

CFM International LEAP-X

|-See also:-External links:* * * *...

 demonstrator engine program, which has completed full-scale rig testing. PowerJet SaM146

PowerJet SaM146

|-See also:-External links:* * * * *...

 engines used on Sukhoi Superjet 100

Sukhoi Superjet 100

The Sukhoi Superjet 100 is a modern, fly-by-wire regional jet in the 75- to 95-seat category. With development starting in 2000, the plane was designed by the civil aircraft division of the Russian aerospace company Sukhoi in co-operation with Western partners...

s are also equipped with blisks.

General Electric

General Electric

General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...

's TechX engines will also use blisks. The GEnx already uses blisks in some stages.

Advantages

Instead of making bare compressor disks and attaching the blades later on in the process, blisks are single elements combining the two. This eliminates the need to attach the blades to the disk (via screws, bolts, etc.), thus decreasing the number of components within the compressor, while at the same time decreasing drag and increasing efficiency of air compression within the engine. In addition, the removal of the dovetail attachment found on traditional turbine blades eliminates a common source for crack initiation and subsequent propagation.

Efficiency improvements of up to 8% are possible.

Disadvantages

Any damage to IBR blades beyond minor dents requires the full removal of the engine so that the IBR may be replaced or, if possible, replacement blades welded on. Maintenance of this nature cannot be done on the flightline and often must be performed at a specialized facility. IBR blades must undergo rigorous harmonic vibration testing as the natural damping of the dovetail attachement of a typical turbine blade is no longer present.

Process

Blisks can be produced with several different manufacturing processes, including CNC milling, Investment casting

Investment casting

Investment casting is an industrial process based on and also called lost-wax casting, one of the oldest known metal-forming techniques. From 5,000 years ago, when beeswax formed the pattern, to today’s high-technology waxes, refractory materials and specialist alloys, the castings allow the...

, electro chemical machining

Electro chemical machining

Electrochemical machining is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for working extremely hard materials or materials that are difficult to machine using conventional methods. Its use is limited to electrically conductive...

, or welding

Welding

Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

.

External links

• Rolls-Royce LiftFan blisk (March, 2003)
• http://www.rolls-royce.com/press/assets/images/defence/tech_blisk.jsp
• http://100.rolls-royce.com/facts/view.jsp?id=283
• http://www.rolls-royce.com/media/showPR.jsp?PR_ID=1342