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The Evolution of Jet Engine Blade Containment Systems
Date: September 18, 2007, 11 a.m. to 12:30 p.m.
Presented By: Mr. Hopkins (NASA Glenn Research Center)
In today's modern commercial jet engines the fan case is among the
largest and heaviest components of the engine. During normal flight the
fan case provides structural support for the inlet/nacelle structure and
confines the fan air flow path. However, in the event of an engine blade
failure the fan case also provides protection to the aircraft structure
by containing any separated fragments within the engine environment. As
engine designs increase in size and power, the lightweight rugged
materials needed to meet this protection requirement is one of the most
challenging issues for new engine developments.
Two design approaches for engine blade containment have evolved over the
years. The original "hardwall" approach requires that the wall of the
fan case structure block and reflect the failed blade fragments. This
approach results in a heavy rigid fan case structure, typically a
thick-walled, stiffened shell-type configuration manufactured of
metallic materials.
The newer "softwall" approach allows the failed blade fragments to
penetrate the fan case structure inner wall and be captured within. This
enables a lighter weight fan case system, such as a sandwich-type
configuration surrounded by a supplemental flexible structure of dry
ballistic fabric.
Two new composite material/structural concepts have been developed that
demonstrate technical feasibility and significant potential benefits
(i.e. 25-50% weight savings with equal or better performance). These
concepts exploit innovative fiber braid preforming and
fiber-reinforced-foam core preforming processes along with advances in
resin transfer molding and vacuum infusion molding processes.
Additionally, new modeling, testing, and inspection methodologies were
developed and demonstrated enabling a more credible and efficient
approach for incorporating these new composite concepts into the
design/development process for real engine fan case/blade containment
system products.
Technical challenges still face this area. Issues such as potential
aging/degradation effects due to cyclic environmental and loading
conditions over long term service are being investigated under the
Aircraft Aging and Durability Project. Adapting the new composite
material and structural concepts for higher operating temperature
capability is being pursued under the Supersonics Project. Of particular
interest are nano-particle enhanced polyimide resins, and polymer
cross-linked aerogels for incorporation into lightweight and durable
structural concepts. The Subsonic Fixed Wing and Supersonics Projects
are studying the inherent material/structural features of the new
composite concepts for more "multi-functional" performance in engine
case/duct structures.
+ See Full Technical Seminar Series Schedule
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