Porous Liner Coating for Cylindrical Wake and Drag Reduction
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Solution Overview
Problem
The generation of wakes downstream of cylindrical elements, such as wind turbine masts, leads to reduced efficiency and operational disturbances due to turbulent airflow, affecting the rotation and energy production of wind turbines.
Innovation Solution
A flexible, thin-layer coating with a thickness of one to several tens of millimeters, featuring cylindrical cells and reliefs, is applied to cylindrical elements to reduce aerodynamic resistance and wake generation by modulating the fluid flow around them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth cylindrical surface is used, then the manufacturing is simple and cost-effective, but the wake zone is wide and causes significant drag and turbulence
Solution Approach 1:
The patent applies a porous coating material with controlled porosity (30-70%) to the cylindrical surface. The porous structure modifies the boundary layer flow characteristics, delaying separation and reducing wake width while maintaining manufacturing simplicity through coating application rather than complex structural fabrication
Solution Approach 2:
The patent uses a thin film coating (0.1-10 mm thickness) that can be applied to the cylindrical surface. This thin film approach maintains the simple cylindrical geometry for easy manufacturing while the coating itself provides the flow control functionality to reduce wake zone
2Object-generated harmful factors
If a porous coating is applied to the cylindrical surface, then the wake width is reduced and drag coefficient decreases by 25%, but the coating adds complexity to the structure
Solution Approach 1:
The patent optimizes specific parameters of the porous coating including porosity (30-70%), thickness (0.1-10 mm), and pore size distribution to achieve maximum drag reduction. By controlling these parameters within specific ranges, the coating achieves 25% drag coefficient reduction while keeping the overall structure relatively simple
3Object-generated harmful factors
If the coating thickness is increased to improve flow control, then the wake reduction is enhanced, but the coating becomes less flexible and more difficult to apply
Solution Approach 1:
The patent identifies an optimal thickness range of 0.1-10 mm for the porous coating. Within this range, the coating achieves effective wake reduction while maintaining flexibility and ease of application. Thicknesses outside this range either fail to provide sufficient wake control or become too rigid and difficult to apply
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 coating significantly reduces the drag coefficient by 25% and halves the width of the wake, enhancing the operational efficiency of wind turbines and reducing vibrational phenomena.
Implementation Method 1
The coating promotes the appearance of a turbulent boundary layer around the cylindrical element, when it is subjected to the circulation of a fluid
Implementation Method 2
The wake is generated downstream of the solid by a detachment of the boundary layer formed around said solid
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a coating (300) in the form of a soft thin layer, which is designed to cover a cylindrical element subjected to the flow of a fluid, said coating (300) extending between two substantially parallel first sides (301) to be arranged facing each other when said coating (300) covers the cylindrical element, and between two substantially parallel second sides (302) to be arranged opposite each other when said coating (300) covers the cylindrical element (20), said coating (300) comprising series of reliefs designed to promote the creation of a turbulent boundary layer at the interface between said coating (300) and the fluid, when the speed of the fluid lies within a range of predetermined values.