Hollow Fan Blade Covers Adhered to Prevent Detachment
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Solution Overview
Problem
Existing fan blades for aircraft engines are heavy, and current methods for creating hollow blades with covers are difficult to manufacture and prone to detachment, leading to issues with stiffness, buckling, and surface conformity, which affect thrust-specific fuel consumption (TSFC) and safety.
Innovation Solution
A hollow fan blade design featuring a body with convex and concave sides, including inner and outer covers that are adhered using epoxy, with features such as recesses and channels to enhance adhesive area and prevent detachment, allowing for multiple thin covers that maintain structural integrity and reduce manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick titanium cover is used to prevent buckling under bird impact, then the structural integrity and stiffness are improved, but the manufacturing difficulty increases and the cover is harder to form
Solution Approach 1:
The cover is divided into multiple thin covers instead of using a single thick cover. This segmentation allows each thin cover to be more easily formed and manufactured while collectively providing the required structural integrity and stiffness when adhered to the blade body.
Solution Approach 2:
Multiple thin covers are combined with adhesive to create a composite structure that achieves the required stiffness and strength. The composite construction allows for easier manufacturing of individual thin covers while maintaining overall structural integrity through the layered assembly.
2Ease of manufacture
If a thin titanium cover is used to improve manufacturability, then the ease of manufacture is improved, but the stiffness is reduced and the cover is more likely to buckle under bird impact
Solution Approach 1:
The cover function is segmented into multiple thin covers that are easier to form individually. Each thin cover can be manufactured with standard forming processes, and when assembled in layers with adhesive, they collectively provide the required stiffness and buckling resistance.
Solution Approach 2:
The thickness parameter of the cover is changed from a single thick cover to multiple thin covers. This parameter change enables easier manufacturing of each individual cover while the cumulative effect of multiple layers maintains the required structural strength.
3Strength
If the cover thickness is increased to prevent buckling, then the structural integrity is improved, but the ability to conform flush to the blade surface is reduced due to surface variations
Solution Approach 1:
The cover is segmented into multiple thin layers that can better conform to surface variations. The thin covers can adapt to the blade surface geometry more effectively, and when adhered in layers, they maintain both surface conformity and buckling resistance.
Solution Approach 2:
Thin cover films are used instead of thick rigid covers. These thin films are more flexible and can conform to the blade surface variations, eliminating dams and waterfalls while maintaining structural integrity through the multi-layer construction.
4Reliability
If the glue area is increased to mitigate detachment risk, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The attachment system is segmented into multiple adhesive bonds between successive thin covers and the blade body. This creates multiple bonding areas that collectively provide high attachment reliability without requiring a single large complex bonding structure.
Solution Approach 2:
The multiple thin covers are nested one on top of another, with each cover adhered to the previous layer. This nested arrangement creates multiple adhesive bonding surfaces that increase overall attachment reliability while maintaining a relatively simple overall structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design results in lighter fan blades with improved TSFC, reduced risk of cover detachment, and easier manufacturing, while maintaining structural integrity and surface conformity, thereby enhancing engine efficiency and safety.
Implementation Method 1
inner and outer covers that are adhered using epoxy
Data Source
AI summary
Hollow fan blades for gas turbine engines are disclosed. The hollow fan blades include a body having a convex side and a concave side wherein the convex side has a cavity formed therein. The cavity is covered by two covers including an inner cover that may be adhered to the body of the fan blade assembly and an outer cover that may be adhered to the inner cover and/or the body of the fan blade assembly. The covers may be made of titanium, more than two covers may be employed and more than one cavity may be employed.