Papers

ICMCTF2006 Session A4: Clearance Control

Thursday, May 4, 2006 3:50 PM in Room Sunrise

Thursday Afternoon

Start	Invited?	Item
3:50 PM		A4-8 Clearance Control and Abradable Coatings in IGT Engines D. Allen (Siemens Power Generation Inc.) At Siemens Power Generation Orlando there are ongoing efforts to reduce interstage leakage in the compressor and turbine sections of our large engines. Reducing leakage is beneficial for both emissions (particularly with regards to NO_x production) and for increased efficiency and power. Blade tip-shroud interstage leakage reduction in Rows 1 and 2 of the turbine is of particular importance and has historically been addressed in aero engines via a combination of porous ceramic coatings and abrasively tipped blades. Industrial gas turbines pose unique challenges for conventional abradable/abrasive systems due to IGT operating cycles, which tend to be longer duration than for aero engines, and their large diameter, which requires physically larger sealing surfaces. Combustor sealing is also a greater problem for IGT’s since most use a can-annular design rather than the annular construction typical of aero engines. This presentation will present several common leakage areas encountered in large industrial gas turbine engines and some general trends in the power generation industry to improve clearances.
4:30 PM		A4-10 Rub Testing Temperature Effects in NiCrAl-Bentonite Abradable T.A. Taylor, W. Aton, B.W. Thompson (Praxair Surface Technologies) A standard flame-sprayed abradable coating intended for later-stage aero compressor sealing was tested at room temperature and at 600°C in a new rub test facility. A range of applicable blade tip speeds and infeed rates were tested in both cases. The relative wear measurements, rub forces and wear mechanisms were compared over this region of the wear map.