Blisk
A blisk (or bladed disk) 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 engine design. The word is a portmanteau of blade and disk, the two components it replaces in turbomachinery. Blisks may also be known as integrally bladed rotors (IBR).
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[edit] History
Blisk manufacturing has been used since the mid 1980s. It was first used by Sermatech-Lehr (now known as GKN Aerospace [1]) in 1985 for the compressors of the T700 helicopter 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 turbofan.
The F-35B variant of the Joint Strike Fighter uses blisks to achieve STOVL.[2]
Engine manufacturer CFM International is using blisk technology in the compressor section of its Leap-X demonstrator engine program, which has completed full-scale rig testing.[3] PowerJet SaM146 engines used on Sukhoi Superjet 100s are also equipped with blisks.[4]
General Electric's TechX engines will also use blisks.[5] The GEnx already uses blisks in some stages.
[edit] 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.[6]
Efficiency improvements of up to 8% are possible.[7]
[edit] 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 attachment of a typical turbine blade is no longer present.[6]
[edit] Process
Blisks can be produced with several different manufacturing processes, including CNC milling, Investment casting, electro chemical machining, or welding.
[edit] References
- ^ http://www.gknaerospace.com/
- ^ "Rolls-Royce's LiftSystem for the Joint Strike Fighter" By Ellie Zolfagharifard, The Engineer 28 March 2011
- ^ Optioning the Future, Aviation Week & Space Technology, 170, 10 (9 March 2009), p. 37
- ^ "Powering Up Next-Gen Engine MRO" By Bill Burchell, Aviation Week. 2 November 2010
- ^ "GE TechX engine set to lead new generation of GE turbofans" By John Croft, Flightglobal. 19 May 2010
- ^ a b O. Younossi, et al., Military Jet Acquisition: Technology Basics and Cost-Estimating Methodology, RAND Corporation, ISBN 0-8330-3282-8, p. 29-30 (2002).
- ^ "NBAA: GE TechX fan blisk is all the buzz" By John Croft, Flightglobal. 21 October 2010
