Wind Turbine Blade Trailing Edge Vortex Control
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Solution Overview
Problem
Modern wind turbine rotor blades are susceptible to edgewise vibrations due to vortex shedding, which can lead to damage when the frequency of vortex shedding matches the blade's eigen frequencies, especially at high angles of attack or when the blades are stationary.
Innovation Solution
The design features a wind turbine blade with a convex trailing edge surface that includes sharp corners and flutes or internal ducts, which reduce vortex shedding by guiding airflow and preventing separation, thereby minimizing the strength and frequency of vortices and associated vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional trailing edge design is used, then the blade structure is simple, but vortex shedding occurs causing edgewise vibrations
Solution Approach 1:
The trailing edge is segmented into multiple flutes or channels that divide the flow path. This segmentation breaks up the coherent vortex structures into smaller, less harmful vortices, reducing the amplitude of unsteady loading and edgewise vibrations while maintaining structural integrity
Solution Approach 2:
The invention introduces a new dimension to the trailing edge by adding spanwise-extending flutes or channels. This dimensional addition creates a three-dimensional flow control structure that actively manages vortex formation and shedding, transforming the two-dimensional trailing edge problem into a three-dimensional solution
2Productivity
If the blade is designed to be long and slender, then the aerodynamic efficiency is improved, but aeroelastic stability issues increase
Solution Approach 1:
The invention applies local quality by modifying only the trailing edge region with flutes or channels, while maintaining the overall long and slender blade geometry. This localized modification provides vortex control and aerodynamic damping precisely where needed (at the trailing edge) without compromising the global aerodynamic efficiency of the blade design
3Ease of manufacture
If a blunt trailing edge is used, then manufacturing is simplified, but flow separation and vortex shedding increase
Solution Approach 1:
The flutes or channels introduced in the trailing edge create curved flow paths that guide the airflow smoothly through the trailing edge region. This curvature prevents abrupt flow separation that would occur with a simple blunt edge, reducing vortex shedding while the overall blunt geometry maintains ease of manufacturing
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 fluid flow-induced forces and vibrations by breaking down vortices into smaller, less coherent structures, dissipating energy and reducing the amplitude of unsteady loading on the blade, thus minimizing the risk of damage from edgewise vibrations.
Implementation Method 1
the flow may separate from the blade giving rise to periodic vortex shedding
Implementation Method 2
the flow may separate from the blade giving rise to periodic vortex shedding form either side of the blade
Data Source
Figure 1
Figure 2
Figure 3a~4b
AI summary
A wind turbine blade extending in a spanwise direction from a root end to a tip end, the blade having a pressure surface and a suction surface, the blade comprising: a truncated trailing edge having a trailing edge surface between the pressure surface and the suction surface; a pressure surface aft corner where the trailing edge surface connects with the pressure surface; a suction surface aft corner where the trailing edge surface connects with the suction surface; wherein the trailing edge surface is curved in cross-section and the truncated trailing edge comprises a plurality of channels.