Fan Rotor Blade Sheath Length Optimization for Impact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fan rotor blades made of composite materials face challenges in achieving sufficient impact resistance without increasing weight or complexity, as providing a guard along the trailing edge complicates the design and reduces aerodynamic performance.
Innovation Solution
Optimizing the sheath length along the leading and trailing edges of the fan rotor blade, with the sheath length at 80% span being equal to or longer than 10% chord and equal to or shorter than 60% chord, and the sheath length along the end edge being equal to or longer than 40% chord, to reduce impact energy and maximum strain without the need for additional reinforcement or thickening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard is provided along the trailing edge to ensure impact resistance, then impact resistance is improved, but device complexity increases and weight increases
Solution Approach 1:
The patent extracts the impact protection function from the trailing edge guard and relocates it to the leading edge sheath. By extending the sheath length along the leading edge to meet specific criteria (80% span sheath length of 10-60% chord, end edge sheath length of 40% chord), the design eliminates the need for a separate trailing edge guard while maintaining impact resistance through the optimized sheath configuration.
Solution Approach 2:
The leading edge sheath is designed to serve multiple functions: it provides aerodynamic smoothing, protects the leading edge from damage, and simultaneously acts as the primary impact protection mechanism. By making the sheath multi-functional, the patent eliminates the need for separate protection components like trailing edge guards, thereby reducing overall device complexity.
2Reliability
If the blade body is made thick to ensure impact resistance, then impact resistance is improved, but aerodynamic performance deteriorates and weight increases
Solution Approach 1:
Instead of uniformly thickening the entire blade body, the patent applies local reinforcement only where needed for impact protection. The sheath is strategically positioned and dimensioned to provide localized impact resistance at the leading edge, while the rest of the blade body maintains its aerodynamic profile. This localized approach ensures impact protection without compromising aerodynamic performance.
Solution Approach 2:
The blade body is constructed using composite materials (thermosetting plastic or thermosoftening plastic with reinforced fiber) that provide high strength-to-weight ratio. This allows the blade to achieve sufficient impact resistance through material selection rather than increasing thickness, thereby maintaining aerodynamic performance while protecting against impact loads.
3Reliability
If the blade body is made thick to ensure impact resistance, then impact resistance is improved, but weight increases
Solution Approach 1:
The patent applies local reinforcement only where needed for impact protection. The sheath is strategically positioned and dimensioned to provide localized impact resistance at the leading edge, while the rest of the blade body maintains its aerodynamic profile. This localized approach ensures impact protection without compromising aerodynamic performance.
Solution Approach 2:
The blade body is constructed using composite materials (thermosetting plastic or thermosoftening plastic with reinforced fiber) that provide high strength-to-weight ratio. This allows the blade to achieve sufficient impact resistance through material selection rather than increasing thickness, thereby maintaining aerodynamic performance while protecting against impact loads.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fan rotor blade includes a blade body constructed of a composite material, a blade root integrally formed at a base end of the blade body by the composite material, and a sheath attached to a leading edge of the blade body so as to extend in a span direction. The sheath includes a sheath main body and a pair of joint flanges, and is segmented into a sheath base segment and a sheath top segment. The sheath top segment smoothly continues from the sheath base segment, and has a longer length than a length of the sheath base segment along a span direction. A sheath length of the sheath main body at an assumed impact position that is a radially outermost position on the sheath top segment to be contacted with an obstacle suctioned into the engine case is not shorter than 10 %chord and not longer than 60 %chord. A sheath length of the sheath along an end edge of the fan rotor blade is not shorter than 40 %chord. The fan rotor blade possesses sufficient impact resistance and can be simplified and light-weighted.