Polygonal Overhead Cable with Flat Projections for Wind Load and Noise
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Solution Overview
Problem
Conventional overhead cables reduce wind load but increase wind noise at medium wind speeds, and vice versa, making it difficult to achieve both wind load reduction and noise reduction simultaneously, especially under strong wind and heavy rain conditions.
Innovation Solution
An overhead cable with a cross-sectional shape of an equilateral polygon and flat-plate-shaped projections on its surface, where the number of angles and diameter of the polygon, along with the height of the projections, are optimized to minimize wind load and noise. The cable's design includes a fundamental cross-sectional shape of an equilateral polygon with specific numbers of angles corresponding to different diameters, and flat-plate-shaped projections with heights between 0.3 mm and 0.75 mm, which are strategically positioned to reduce wind pressure and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If spiral grooves are formed on the outer circumferential surface to reduce wind load, then wind load is reduced at strong wind, but wind noise increases at medium wind speed (10-20 m/s)
Solution Approach 1:
The invention applies different surface features to different parts of the cable: spiral grooves are formed on the windward side (front half) to reduce wind load, while spiral projections are formed on the leeward side (rear half) to reduce wind noise. This local differentiation allows each side to address its specific problem without compromising the other function.
Solution Approach 2:
The cable surface features are designed asymmetrically with grooves on the windward side and projections on the leeward side. This asymmetric configuration optimizes aerodynamic performance by having the grooves capture and redirect wind flow at the front, while the projections at the rear suppress vortex formation and reduce noise, achieving both wind load reduction and noise control.
2Object-generated harmful factors
If the size of spiral projections is increased to reduce wind noise, then wind noise is reduced, but drag coefficient becomes large and wind load reduction effect is deteriorated
Solution Approach 1:
Spiral projections are placed only on the leeward side (rear half) of the cable rather than uniformly across the entire surface. This localized placement allows the projections to reduce wind noise through vortex suppression at the critical rear region, while minimizing their impact on the overall drag coefficient and wind load.
Solution Approach 2:
The spiral projections are applied partially (only on the leeward side) rather than excessively (full circumference). This partial application is sufficient to achieve wind noise reduction at the noise-generating rear region, while avoiding the penalty of increased drag that would result from full-circumference projections.
3Ease of manufacture
If conventional round cable design is used, then manufacturing is simple, but wind load and wind noise cannot be simultaneously reduced
Solution Approach 1:
The cable surface is segmented into two functional zones: the windward side with spiral grooves for wind load reduction, and the leeward side with spiral projections for wind noise reduction. This segmentation allows each zone to perform its specific function optimally, achieving simultaneous reduction of both wind load and wind noise that cannot be accomplished with a uniform round design.
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 solution effectively reduces wind pressure load and wind noise at medium wind speeds, maintaining a balance between wind load reduction and noise suppression, even under conditions of strong wind and heavy rain, by using an equilateral polygon shape with optimized angles and projection heights, resulting in a more practical and environmentally friendly overhead cable design.
Implementation Method 1
an overhead cable which is less subject to a wind load under conditions of strong wind in a typhoon or the like
Implementation Method 2
which can furthermore reduce wind noise at a medium wind speed
Data Source
AI summary
An overhead cable including a plurality of element wires stranded to form a naked stranded cable, which has a cross-sectional shape of an equilateral polygon inscribed in a circle having a diameter of 18.2 mm to 38.4 mm as a fundamental cross-sectional shape, in which two sides of this equilateral polygon that are located at positions farthest from each other are outwardly projected, has two flat-plate-shaped projections corresponding to the two sides, wherein the number of angles of the equilateral polygon is set depending to the diameter of the circle.