AIRFOIL LEADING EDGE GUARD
Publication Date: 2017-Mar-09
The IP.com Prior Art Database
A metal leading edge guard for a composite airfoil incorporates scallops to reduce its stiffness and preserve the adhesive bond between the leading edge guard and the airfoil.
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AIRFOIL LEADING EDGE GUARD
 A metal leading edge guard for a composite airfoil incorporates scallops to reduce
its stiffness and preserve the adhesive bond between the leading edge guard and the
 A typical aircraft engine includes numerous components which have a leading
edge facing a high-velocity air flow. Some of these components are made from
nonmetallic materials such as carbon fiber composites. While these materials are strong,
stiff, and have good strength-to-weight ratios, they can require protection from impacts of
foreign objects entrained in the airflow.
 One particular example of this type of component is an outlet guide vane. In a
turbofan engine, outlet guide vanes are a ring of airfoils that are disposed immediately
downstream of the fan blades and serve the purpose of straightening the flow exiting the
fan. To protect the outlet guide vanes, a metal leading edge guard is bonded to the
composite outlet guide vane using an adhesive.
 In operation, the outlet guide vanes vibrate because of aeromechanical effects.
They vibrate in multiple modes, resulting in leading edge deflection side-to-side and, to a
lesser extent, forward and aft.
 One problem with existing leading edge guards is that the deflection of the
outlet guide vane drives the metal leading edge to deflect, but because of the metal
leading edge guard's internal stiffness, strain develops in the thin layer of adhesive. This
can lead to dis-bonding (delamination) and subsequent cracking and loss of metal leading
edge guard material.
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 Described herein is a leading edge guard configured to have reduced bending
moment of inertia (i.e. bending stiffness), for the purpose of protecting the integrity of the
adhesive bond between the leading edge guard in the composite structure.
BRIEF DESCRIPTION OF THE DRAWINGS
 The concept may be best understood by reference to the following description
taken in conjunction with the accompanying drawing figures in which:
 FIG. 1 is a schematic half-sectional view of a gas turbine engine;
 FIG. 2 is a schematic side elevational view of an exemplary outlet guide vane
with a leading edge guard attached thereto;
 FIG. 3 is an end view of the guide vane of FIG. 2;
 FIG. 4 is an end view of the leading edge guard shown in FIG. 2 ; and
 FIG. 5 is front elevational view of the leading edge guard of FIG 4.
DETAILED DESCRIPTION OF THE CONCEPT
 Referring to the drawings wherein identical reference numerals denote the same
elements throughout the various views, FIG. 1 depicts an exemplary gas turbine engine
10. While the illustrated example is a high-bypass turbofan engine, the principles of the
present invention are also applicable to other types of engines, such as low-bypass
turbofans, turbojets, turboprops, etc. The engine 10 includes a fan 12, booster 14,
compressor 16, combustor 18, high pressure turbine 20, and low pressure turb...