A consortium of nine European companies and research centres has launched a four-year project to develop advanced coatings for aero-engine turbine blade-tips. The work is aimed at achieving reduced tip-clearances, to improve engine performance without causing excessive wear in the blades.
"When the blade tip rubs against the stator, it can wear the blade tip, which is bad for the performance of the engine," says Philippe Walter, deputy manager for materials and coatings at France's Turboméca, which is co-ordinating the project. "The problem is how to keep the smallest possible gap between the rotor and stator without wearing the blade tip," Walter adds.
The ECU4 million ($5 million) Advanced Abradable Tip Coating for Gas Turbines (Abratip) project is 50% funded by the European Union, and consists of two phases.
The first involves assessing the performance of existing engines, while the second is aimed at developing advanced composite coatings, and "optimising them before a final choice of the best", according to Walter.
UK coatings specialist Poeton is a member of the consortium, and its research-and-development team is working on a new alloy plating as part of the Abratip project. "The performance of an aircraft engine is highly dependent upon the interaction between the blade tips and the engine casing," says Keith Stevens, senior tribologist at Gloucester, UK-based Poeton.
"As the engine gets hot, the blades must be able to machine their own clearance within the stator while themselves suffering no damage. This requires a highly specialised composite coating on the blade tips," he adds.
Other members of the consortium include BMW Rolls-Royce and MTU of Germany, France's Snecma, Sulzer of Switzerland and Belgium's Techspace Aero. French and German research centres, based in Lyon and Berlin, respectively, are also involved in the Brite Euram project, due to be completed in June 2000.
Source: Flight International
