Asymmetric Riblet Structure for Drag Reduction Without Fragility
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Solution Overview
Problem
Conventional plate-shaped riblets thinned to the processing limit are structurally fragile and unsuitable for practical use due to lack of sufficient strength.
Innovation Solution
A riblet structure comprising a plurality of riblets with a first wall portion perpendicular to a base and a second wall portion including an inclined portion at a predetermined angle, allowing for enhanced strength and reduced surface friction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If plate-shaped riblets thinned to the processing limit are formed to maximize surface friction resistance reduction, then the surface friction resistance can be reduced by approximately 10% at a maximum, but the riblets become structurally fragile and are not suitable for practical use
Solution Approach 1:
The patent changes the geometric parameters of the riblet structure by introducing an inclination angle (20°-60°) for the second wall portion instead of using plate-shaped riblets thinned to the limit. This parameter modification maintains the drag reduction effect while significantly improving structural strength and practical applicability
Solution Approach 2:
The patent employs asymmetric riblet geometry where the second wall portion is inclined at a predetermined angle rather than being symmetric or plate-shaped. This asymmetric design creates optimal flow control for drag reduction while providing sufficient structural integrity for practical use
2Object-affected harmful factors
If the apex portion angle is sharpened to reduce surface friction resistance, then the resistance reduction increases, but the riblet structure becomes more fragile
Solution Approach 1:
The patent optimizes the apex portion angle within a specific range (20°-60°) rather than sharpening it to the limit. This parameter optimization achieves effective drag reduction while maintaining structural reliability and preventing excessive fragility
Solution Approach 2:
The patent applies partial sharpening of the apex portion within an optimal angle range rather than excessive sharpening to the limit. This partial action achieves sufficient drag reduction effect while avoiding the structural fragility that would result from over-sharpening
Data Source
AI summary
A riblet structure according to the present technology includes a plurality of riblets that are arranged in a width direction and each include a first wall portion and a second wall portion, the first wall portion being vertically provided to be substantially perpendicular to a bottom portion, the second wall portion including an inclined portion connected to the first wall portion at an apex portion and inclined with respect to a perpendicular direction at a predetermined angle.