Wind Turbine Rotor Blade Chord Slope Optimization
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Solution Overview
Problem
Conventional wind turbine rotor blades experience flow separation at high wind speeds, leading to increased noise and structural loads, which affects their efficiency and performance.
Innovation Solution
The design optimizes the chord slope and radius of curvature of the rotor blade, particularly in the transitional region, to reduce loads and noise, with a larger tip chord and a more favorable induced angle of attack, ensuring a thinner boundary layer and improved aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional rotor blade design is used, then structural strength is maintained, but flow separation occurs at high wind speeds leading to increased noise and reduced aerodynamic efficiency
Solution Approach 1:
The patent applies parameter changes by optimizing the chord slope (first derivative of chord with respect to span) and radius of curvature in the transitional region. Specifically, the chord slope is constrained to range from -0.10 to 0.10, and the radius of curvature is maintained above 2mm, which modifies the boundary layer development and prevents flow separation, thereby reducing noise while maintaining aerodynamic efficiency
Solution Approach 2:
The patent applies local quality by focusing the geometric optimizations specifically in the transitional region (inboard region) of the rotor blade, rather than uniformly across the entire blade. The chord slope and radius of curvature constraints are applied locally to the inboard region spanning from 0% to 40% of the blade span, allowing different regions of the blade to have optimized characteristics for their specific functional requirements
2Force
If thicker boundary layer is allowed, then structural loads are reduced, but flow separation increases leading to higher noise
Solution Approach 1:
The patent uses parameter changes by establishing specific constraints on the chord slope (first derivative) and radius of curvature in the transitional region. These geometric parameters directly influence boundary layer thickness and stability. By constraining the chord slope to -0.10 to 0.10 and radius of curvature to greater than 2mm, the design achieves a thinner, more stable boundary layer that resists separation while managing structural loads
3Object-affected harmful factors
If tip chord is reduced, then noise is decreased, but aerodynamic performance and energy extraction are compromised
Solution Approach 1:
The patent applies local quality by differentiating the geometric constraints between the inboard region (0-40% span) and outboard region (40-100% span). The transitional region in the inboard area has specific chord slope and radius of curvature constraints to control boundary layer and reduce noise, while the outboard region including the tip maintains characteristics optimized for energy extraction, achieving a balance between noise reduction and power generation
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 reduces noise and structural loads, enhances aerodynamic efficiency, and maintains performance by minimizing flow separation and tip chord unloading, resulting in improved energy extraction and reduced joint complexity.
Implementation Method 1
The rotor blades have a cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between the sides. Consequently, a lift force, which is directed from a pressure side towards a suction side, acts on the rotor blade.
Implementation Method 2
A blade section extracts much less energy from the flow when it separates.
Data Source
AI summary
A rotor blade assembly of a wind turbine includes a rotor blade having an aerodynamic body with an inboard region and an outboard region. The inboard and outboard regions define a pressure side, a suction side, a leading edge, and a trailing edge. The inboard region includes a blade root, whereas the outboard region includes a blade tip. The rotor blade also defines a chord and a span. Further, the inboard region includes a transitional region of the rotor blade that includes a maximum chord. Moreover, a unitless first derivative of the chord with respect to the span of the rotor blade in the transitional region ranges from about −0.10 to about 0.10 from the maximum chord over about 15% of the span of the rotor blade. In addition, the unitless first derivative of the chord with respect to the span a slope of a change in the chord in is greater than about −0.03 at an inflection point of the chord in the outboard region.