Objectives and content
Gas turbine efficiency is significantly influenced by the pressure losses caused by the inevitable gap between the rotating turbine blades and the stator parts.
Because contact between rotor and stator cannot be completely avoided with a small gap, systems are designed to allow for some rubbing. Honeycombs or abradable MCrAlY stator coatings are normally used to minimize the wear of the rotor blades when rubbing occurs. But, more efficient solutions must be developed on modern engines, because both suffer temperature limitation and standard MCrAlY have usually poor abradability. For higher temperature and closer control of the gap, a thick thermal-barrier coating must be applied on the stator, but presently with no rub-tolerance.
To increase the abradability of the stator coating, its composition and structure can be modified, but such changes must be strictly limited with respect to the loss of erosion resistance.
The solution can then lie in the hardening of the rotating blade tip to permit the use of harder ceramic or metallic coatings on the stator with greater resistance to erosion. These systems typically consist, on the blade tip, of hard particles embedded in a softer metallic matrix.
In the present programme, it is therefore intended:
- to assess the present European solutions, standard or in development, for outer air seals and blade tips.
- to develop coated grits or new grits for the hardening of the blade tips, as well as to improve the matrix and the stator coating for long life systems.
- to optimize the most promising of these systems, that will be tested on development rigs and on engine.
The consortium includes several engine manufacturers, which are the potential users of the innovating solutions to be developed, companies having a large experience in the field of abradables and tip coatings
and non industrial partners involved in tribology and materials science.
Funding SchemeCSC - Cost-sharing contracts
SO49 9DY Southampton