A blisk (

portmanteau A portmanteau word, or portmanteau (, ) is a blend of wordsturbomachine component comprising both rotor disk and blades. It serves as a critical component of the engine compressor to allow a sufficient quantity of compressed air to enter the engine for combustion to occur. Blisks generally have better aerodynamics than conventional rotors with single blades and are lighter. Each blisk consists of a single part instead of disk assembled with individual removable blades. They may be additively manufactured, integrally cast, machined from a solid piece of material, or made by welding individual blades to a rotor disk. The term is used mainly in

aerospace Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astr ...

engine design. ''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 Ltd is a British multinational automotive and aerospace components business headquartered in Redditch, England. It is a long-running business known for many decades as Guest, Keen and Nettlefolds. It can trace its origins back to 1759 an ...

Aerospace) in 1985 for the compressors of the T700

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

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 The Aerojet Rocketdyne RS-68 (Rocket System 68) is a liquid-fuel rocket engine that uses liquid hydrogen (LH2) and liquid oxygen (LOX) as propellants in a gas-generator power cycle. It is the largest hydrogen-fueled rocket engine ever flown. I ...

rocket engine and the

General Electric F110 The General Electric F110 is an afterburning turbofan jet engine produced by GE Aviation. The engine is derived from the General Electric F101 and shares its core design, and primarily powers tactical fighter aircraft. The F118 is a non-afterb ...

turbofan. The F-35B variant of the

Joint Strike Fighter Joint Strike Fighter (JSF) is a development and acquisition program intended to replace a wide range of existing fighter, strike, and ground attack aircraft for the United States, the United Kingdom, Italy, Canada, Australia, the Netherlands ...

uses blisks to achieve

short take-off and vertical landing A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically if it does not have a heavy payload) and land vertically (i.e. with no runway). The ...

. Engine manufacturer

CFM International CFM International is a 50/50 Franco-American joint venture between GE Aviation and Safran Aircraft Engines (formerly known as Snecma). It was formed to build and support the CFM56 series of turbofan engines. The company is the world’s lead ...

is using blisk technology in the compressor section of its Leap-X demonstrator engine program, which has completed full-scale rig testing. PowerJet SaM146 engines used on

Sukhoi Superjet 100 The Sukhoi Superjet 100 () or SSJ100 is a regional jet designed by Russian aircraft company Sukhoi Civil Aircraft, a division of the United Aircraft Corporation (now: Regional Aircraft – Branch of the Irkut Corporation). With development start ...

s are also equipped with blisks.

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable en ...

's Passport (formerly "TechX") engine uses blisks for both its main 52" fan as well as for 5 of its 10 high pressure turbine stages.. The

GEnx The General Electric GEnx ("General Electric Next-generation") is an advanced dual rotor, axial flow, high-bypass turbofan jet engine in production by GE Aviation for the Boeing 787 and 747-8. The GEnx is intended to succeed the CF6 in GE's pro ...

already uses blisks in some stages. Engine manufacturer EDAC Technologies, now

Hanwha Aerospace , type = Public , traded_as = , industry = Aerospace , genre = , fate = , predecessor = , successor = , founded = (as Samsung Precision) ...

USA is the number one global supplier of blisk and IBR manufacturing in the world.

Advantages

First stage Allison axial compressor blisk

Instead of making bare compressor disks and attaching the blades later, 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 in the compressor, while at the same time decreasing drag and increasing efficiency of air compression in the engine. The elimination of the dovetail attachment found on traditional turbine blades eliminates a source for crack initiation and subsequent propagation.. Efficiency improvements of up to 8% are possible.

Disadvantages

Any damage to integrally bladed rotor blades beyond minor dents requires the full removal of the engine so that the rotor 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. Integrally bladed rotor blades must undergo rigorous harmonic vibration testing as well as dynamic balancing to an extremely high standard, since the natural damping of the dovetail attachment of a typical turbine blade is no longer present.

Process

General

Blisks can be produced with several different manufacturing processes, including

CNC Numerical control (also computer numerical control, and commonly called CNC) is the automated control of machining tools (such as drills, lathes, mills, grinders, routers and 3D printers) by means of a computer. A CNC machine processes a p ...

milling,

investment casting Investment casting is an industrial process based on lost-wax casting, one of the oldest known metal-forming techniques. The term "lost-wax casting" can also refer to modern investment casting processes. Investment casting has been used in var ...

, electro chemical machining,

3D printing 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...

, or

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as bra ...

. Research is being conducted to produce them using

friction welding Friction welding (FRW) is a solid-state welding process that generates heat through mechanical friction between workpieces in relative motion to one another, with the addition of a lateral force called "upset" to plastically displace and fuse the m ...

of "near net" part shapes that are then machined down to the final blisk shape.

Measurement and inspection

The measurement and inspection of blisks is crucial for guaranteeing engine performance carried out at the end of the manufacturing processes. Traditionally this has been achieved using tactile devices, like

CMMs A computerized maintenance management system (CMMS), also known as a computerized maintenance management information system (CMMIS), is any software package that maintains a computer database of information about an organization's maintenance o ...

, but as geometries and requirements increase, the trend in modern factories is to carry out 3D scanning using systems like ATOS ScanBox. This has advantages of the speed of measurement compared to tactile devices, whilst collecting 3D data to relate back to design characteristics. Using 3D data, parts can be catalogued in this way, often called digital twin, allowing monitoring of the product through its life-cycle.

Blisk repair using adaptive machining

Engine-run blisks pose their own set of unique requirements. After parts have been in service in the engine, noticeable amounts of damage and wear will be observed. Provided that the damage and wear are within thresholds set by the design authority, it is possible that the blisks can repaired. Repair of blisk components is complex and first requires an accurate 3D representation of the component. The quickest way to do this is by 3D scanning the product. After the part is scanned, an STL file can be passed to a CNC code generating software such as NX CAM. The tool paths are regenerated to suit the measured geometry and not the nominally generated CAD in a process known as adaptive machining. The processes would typically involve removing part or all of a blade(s), followed by a weld back to approximate size before finishing by final machining back to the airfoil shape.

References

External links

* . * . * {{Citation , publisher = Rolls-Royce , url = http://www.rolls-royce.com/media/showPR.jsp?PR_ID=1342 , title = Media , url-status = dead , archiveurl = https://web.archive.org/web/20060921063732/http://www.rolls-royce.com/media/showPR.jsp?PR_ID=1342 , archivedate = 2006-09-21 . Gas turbine technology Engine technology