Vortex Generators Aligned with Serrated Wind Turbine Blade Trailing Edges
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Solution Overview
Problem
Wind turbine noise and drag limitations due to trailing edge aerodynamic noise and vortex generator noise and drag in existing designs, which reduce efficiency and performance.
Innovation Solution
A wind turbine blade design featuring a coordinated alignment of vortex generators with serrated trailing edge features, forming a waveform profile, to produce vortices that cross the trailing edge at specific angles, reducing noise and drag by minimizing acoustic impedance mismatch and flow separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vortex generators are mounted on the suction side to energize the boundary layer and delay flow separation, then aerodynamic efficiency is improved, but noise and drag increase
Solution Approach 1:
The patent positions vortex generators upstream of trailing edge serrations so that the vortices they generate are swept downstream by the serrations. This converts the harmful noise and drag that would be generated by the vortex generators into a beneficial arrangement where the serrations mask the vortex generator signatures, reducing overall noise while maintaining the flow energizing benefits
Solution Approach 2:
The trailing edge serrations act as an intermediary element between the vortex generators and the free stream. The serrations intercept and modify the vortices before they interact with the free stream, reducing the acoustic impedance mismatch and thereby reducing the noise and drag generated by the vortex generators
2Object-affected harmful factors
If blade tip speed is reduced to limit noise, then noise is reduced, but turbine performance capacity is reduced
Solution Approach 1:
The patent uses trailing edge serrations to convert the harmful noise generated by trailing edge aerodynamic interactions into a beneficial outcome. The serrations reduce the acoustic impedance mismatch at the trailing edge, thereby reducing noise without requiring reduction of blade tip speed, thus maintaining turbine performance capacity
Solution Approach 2:
The patent changes the geometric parameters of the trailing edge by introducing serrations with specific wavelengths and amplitudes. This modifies the acoustic impedance characteristics of the trailing edge, reducing noise generation while allowing the blade to operate at higher tip speeds and maintain performance capacity
3Object-affected harmful factors
If trailing edge serrations are used to reduce trailing edge noise, then noise is reduced, but device complexity increases
Solution Approach 1:
The patent segments the trailing edge into multiple serrations rather than using a straight trailing edge. This segmentation reduces the acoustic impedance mismatch by creating gradual transitions in the flow, thereby reducing trailing edge noise. The segmented structure is achieved through repeating geometric patterns that can be manufactured using standard techniques
Solution Approach 2:
The trailing edge serrations are arranged in a periodic pattern along the span of the blade. This periodic structure creates consistent flow modifications that reduce noise while maintaining manufacturing simplicity through repetition of the same geometric element throughout the blade span
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 design achieves reduced noise and drag, enhancing efficiency and performance by delaying flow separation and smoothing airflow, allowing higher angles of attack without stall, while maintaining aerodynamic benefits.
Implementation Method 1
Vortex generators are mounted on the suction side of an airfoil to induce vortices that entrain kinetic energy from the bulk airflow into the boundary layer flow immediately against the suction side surface
Implementation Method 2
induce vortices that entrain kinetic energy from the bulk airflow into the boundary layer flow
Implementation Method 3
trailing edge serrations, as illustrated in FIG. 5 herein, which reduce the abruptness of the acoustic impedance mismatch between the merging suction side and pressure side flows at the trailing edge
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A wind turbine blade (80, 82) having a spanwise series of vortex generators (26, 28, 26P, 28P, 64, 66) and having a trailing edge (42) defining a waveform. The vortex generators are aligned with a predetermined position or phase (44, 46) of a respective period of the trailing edge waveform. Each vortex generator may be designed to create a vortex (27, 29) that crosses the trailing edge at an angle of less than 30 degrees from parallel to the trailing edge. The blade may include alternating ridges (52) and troughs (54) that end at the waveform trailing edge. A front end of each trough may form a V-shaped drop-off in the suction side of the blade that forms a pair (64, 66) of vortex generators to create counter-rotating vortices within the trough that entrain energy to the bottom of the trough.