Project Title:

Shape Memory Alloy Adaptive Control of Gas Turbine Engine Blade Tip

Memry Technologies, Inc.
57 Commerce Drive
Brookfield, CT 06804

93-1-01.02   7311  __      AMOUNT REQUESTED $69,637

Shape Memory Alloy Adaptive Control of Gas Turbine Engine Blade Tip
Clearance.

Abstract:

Blade tip clearance in a gas turbine is critical; each increment of
tip clearance reduction increases efficiency and reduces fuel
consumption. In this study only the compressor section will be
treated. Using a Lycoming T55L-712 turboshaft engine, which has
wide commercial and military application, two stages of the
compressor section will be modified to accept a shape memory alloy
ring whose inner diameter changes with temperature. The compensator
ring will be fabricated of an alloy whose transformation
temperature is suited to the stage 2 and stage 3 of this turbine,
and the design and thermo-mechanical processing of the ring will be
such that when the turbine has reached operating temperature, the
ring diametral change will reduce the tip clearance to
approximately 0.001". Performance will be evaluated for a range of
ambient air temperatures encountered, and the stability of the
compensator ring as a function of cycles of operation and dwell
time at operating temperature. The tip clearance compensation by
the shape memory induced diameter change of a ring insert would
substantially improve engine efficiency and fuel consumption.
Systems for accurately locating the rings in the shroud in both the
axial and radial direction will be developed as well as concepts to
facilitate assembly. Considerations will be given to extending the
concept to the entire compressor section.

An adaptive turbine tip clearance control requiring no external
power source offers efficiency improvement without impacting on
engine reliability or service life. Even small improvements in
specific fuel consumption have an economic impact. The
international market for gas turbines is large, and the competitive
position of U.S. turbine makers is aided by each increment of
improvement in performance.

Shape Memory Alloys, Turbine Tin Clearance Control