Twisted Tapered Wind Turbine Blade Tips for Noise and Power
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Solution Overview
Problem
Conventional wind turbine blades face challenges in balancing power performance and noise reduction, as tip unloading techniques often result in significant power loss and increased noise due to vortex development at the blade tip.
Innovation Solution
The implementation of a blade design with a total backward twist of between approximately 6 degrees and 15 degrees over an outer 1 to 10 percent of the rotor radius, along with specific tip twist and chord distributions that maintain a larger chord length and gradual aerodynamic loading reduction, optimizing power performance and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If tip unloading techniques are applied to reduce noise, then tip-related noise is reduced, but power performance deteriorates significantly
Solution Approach 1:
The patent applies different geometric properties to different parts of the blade tip. Specifically, it implements a backward twist (changing the angle of attack locally at the tip) and a tapered chord reduction (gradually reducing the blade width) only in the outer 1-10% of the rotor radius, while maintaining optimal geometry in the inner regions. This localized modification reduces vortex formation and noise at the tip without significantly impacting the power-generating sections of the blade.
2Object-affected harmful factors
If backward twist is increased to reduce noise, then tip-related noise is reduced, but aerodynamic efficiency deteriorates
Solution Approach 1:
The patent applies a moderate backward twist of only 1-10 degrees in the outermost 1-10% of the rotor radius, rather than applying large twist angles throughout the entire blade span. This partial application of backward twist is sufficient to reduce tip vortex intensity and noise while minimizing the negative impact on aerodynamic efficiency. The limited extent of the twist modification ensures that the majority of the blade maintains high aerodynamic efficiency.
3Object-affected harmful factors
If chord length is reduced at the tip to unload the tip, then noise is reduced, but power performance deteriorates
Solution Approach 1:
The patent implements a gradual tapered reduction of the chord length starting from the blade root and continuing through the mid-span, with the most significant reduction occurring in the outer 1-10% of the rotor radius. This preliminary and gradual tapering prepares the airflow for the tip region, reducing the intensity of tip vortices and associated noise while maintaining adequate chord length in the power-generating regions to preserve power performance.
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
This design enhances power performance, reduces tip-related noise, and increases robustness against turbulence, while allowing for higher precision manufacturing and improved aerodynamic sensitivity, balancing sharp aerodynamic loading drops with gradual reductions for optimal performance.
Implementation Method 1
The blades 10 generate lift and capture momentum from moving air that is them imparted to a rotor as the blades spin in the ' rotor plane.'
Implementation Method 2
tip unloading techniques often result in significant power loss and increased noise due to vortex development at the blade tip
Data Source
AI summary
A blade for a wind turbine includes a total backward twist of between approximately 6 degrees and approximately 15 degrees between an outer approximately 1 percent to 10 percent of a rotor radius of the blade; and an approximate planform distribution within the following rangesr/Rc/R(LE)c/R(TE).960.60 to 0.65%−1.42 to −1.34%.9680.54 to 0.59%−1.31 to −1.34%.9740.39 to 0.58%−1.36 to −1.22%.98060.13 to 0.57%−1.45 to −1.06%.9856−0.23 to 0.56% −1.56 to −0.74%.9906−0.76 to 0.55% −1.74 to −0.24%.9956−1.44 to 0.54% −1.99 to 0.23% 1.00−2.17 to 0.54% −2.27 to 0.44% where “r/R” is an approximate normalized distance outward from a center of rotation of the blade along a span of the blade; and “c/R(LE)” and “c/R(TE)” are approximate relative positions of a leading (LE) and trailing edge (TE) of a chord “c” expressed as a percentage of a distance outward from the center of rotation at each r/R.