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· Orientation of the grain boundaries
of a blade along the tensile axis, or their removal in a single crystal
blade, gets rid of grain boundary sliding as a component of high temperature
creep and, thus, increases useful blade life.
· Turbine working temperature can be further increased
if the blade is cooled internally. The Allison single-crystal, cast Lamilloy
blade shown has laser drilled holes and integral internal ducts to provide bypass
air for film cooling of the blade surface.
· Higher turbine inlet temperatures require ceramic blade-coatings
to reduce heat transfer to the blade structure. |
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