Serrated Foil Edge Profiles for Noise Reduction
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Solution Overview
Problem
Current technologies fail to effectively reduce leading-edge noise in aerofoils, which is a significant source of noise in various applications, and the optimal serration geometry for noise reduction has not been determined.
Innovation Solution
The development of serrated profiles for leading and trailing edges of foils, featuring specific tooth edge geometries with defined chord-wise and span-wise positions, and gradients that maximize noise reduction by avoiding stationary points and concentrating sharpness at tip and root points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional sawtooth serrations are used on foil edges, then some noise reduction is achieved, but the noise reduction effectiveness is insufficient and no optimal geometry has been determined
Solution Approach 1:
The patent applies local quality by concentrating sharpness at specific locations (tip and root points) rather than uniformly across the entire tooth edge. The tooth edge profile is designed to be smooth in intermediate regions while maintaining sharp features at critical points, optimizing noise reduction effectiveness without requiring complex geometry throughout the entire structure.
Solution Approach 2:
The patent employs curved tooth edge profiles instead of straight lines, using ogee-shaped curves that provide smooth transitions while concentrating geometric features at tip and root points. This curvature approach achieves superior noise reduction compared to conventional straight-edged sawtooth serrations.
2Object-generated harmful factors
If serration sharpness is increased to improve noise reduction, then noise reduction effectiveness increases, but manufacturing complexity and difficulty increase
Solution Approach 1:
The patent concentrates the manufacturing challenge of sharpness to only two specific locations (tip and root points) rather than requiring the entire tooth edge to be sharp. The intermediate portions of the tooth edge are intentionally designed to be smooth, significantly reducing manufacturing complexity while maintaining noise reduction effectiveness.
Solution Approach 2:
The use of ogee-shaped curved profiles provides smooth transitions that are easier to manufacture than sharp angular transitions, while still achieving the desired concentration of sharpness at critical points through controlled curvature variations.
3Object-generated harmful factors
If uniform sharpness is applied along the entire tooth edge, then noise reduction is maximized, but the complexity of defining and manufacturing the profile increases
Solution Approach 1:
The patent deliberately avoids uniform sharpness by applying it only locally at tip and root points. The intermediate regions are designed with smooth profiles, creating a non-uniform distribution of geometric features that reduces profile complexity while maintaining noise reduction effectiveness.
Solution Approach 2:
The ogee-shaped curved profile provides a mathematically simple yet effective way to achieve smooth intermediate regions while concentrating sharpness at endpoints, reducing the overall complexity of the tooth edge profile definition.
Data Source
AI summary
A foil, such as an aerofoil, having a leading edge and a trailing edge, of which at least a portion of one or both of the leading edge and trailing edge has a serrated profile comprising a plurality of adjoining teeth, each tooth having a tip point that represents a local maximum chord-wise extent of the tooth and, on each side span-wise of the tip point, a root point that represents a local minimum chord-wise extent of the tooth and at which the tooth adjoins a respective adjacent tooth, wherein the tooth edge profile varies with an ogee-like curve between tip point and root point such that the tooth is sharper in the neighbourhood of the tip point and in the neighbourhood of the root point than at locations in between.