Wind Turbine Rotor Blade Tip Airfoil Design
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Solution Overview
Problem
Wind turbine blades face challenges in reducing aerodynamic loads and weight loads while maintaining aerodynamic performance as they increase in size, with existing methods limited to adjusting blade thickness ratios, which can lead to decreased lift/drag ratios and increased centrifugal forces.
Innovation Solution
The wind turbine rotor incorporates a blade tip section with specific airfoil configurations, including blade thickness ratios, chord-wise distance ratios, and shear web arrangements to reduce spar cap usage, maintaining aerodynamic performance and structural strength while minimizing weight loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the blade thickness ratio is increased to reduce aerodynamic load and weight, then the structural strength is improved, but the aerodynamic performance (lift/drag ratio) deteriorates
Solution Approach 1:
The patent applies different thickness ratios at different radial positions of the blade. The blade tip section (r/R ≥ 0.7) uses a higher thickness ratio (19-23%) to reduce weight and centrifugal force effects, while other sections use lower thickness ratios optimized for their specific aerodynamic requirements. This local differentiation allows each section to have optimal properties for its function.
Solution Approach 2:
The patent changes the geometric parameters of the airfoil, specifically the thickness ratio and the position of maximum thickness (Xtmax/C), to optimize performance. By setting the maximum thickness position at 28-32% of the chord length and the thickness ratio at 19-23% in the blade tip section, the patent achieves a balance between structural requirements and aerodynamic efficiency.
2Weight of moving object
If the blade thickness ratio is increased to reduce spar cap usage and weight, then the weight load is reduced, but the aerodynamic load increases
Solution Approach 1:
The patent implements local quality by applying a higher thickness ratio (19-23%) specifically to the blade tip section where r/R ≥ 0.7, while other sections of the blade use lower thickness ratios. This localized approach allows weight reduction where it matters most (blade tip) without compromising the aerodynamic performance of other critical sections.
Solution Approach 2:
The patent optimizes the dynamic characteristics of the blade by adjusting the thickness distribution to reduce centrifugal forces acting on the blade tip. The increased thickness at the tip reduces the need for heavy spar caps, thereby reducing the overall weight and dynamic loads during rotation.
3Ease of manufacture
If the blade thickness ratio is increased to reduce spar cap usage, then the manufacturing cost is reduced, but the aerodynamic efficiency decreases
Solution Approach 1:
The patent applies local quality by restricting the higher thickness ratio (19-23%) to the blade tip section (r/R ≥ 0.7) only, while other sections use lower thickness ratios optimized for their aerodynamic requirements. This localized application reduces material usage and manufacturing cost in the critical tip region without compromising overall aerodynamic efficiency.
Solution Approach 2:
The patent changes the geometric parameters of the airfoil in the blade tip section, specifically setting the thickness ratio to 19-23% and the maximum thickness position (Xtmax/C) to 28-32%, which optimizes the balance between structural requirements, aerodynamic performance, and manufacturing considerations for that specific region.
Data Source
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AI summary
At least a part of a region of a blade tip section (14), in which at least one shear web exists, has an airfoil satisfying all of conditions: (a) a blade thickness ratio is not less than 19% and not greater than 23%; (b) a Xtmax/C of Xtmax to a chord length C is not less than 0.28 and not greater than 0.32 where Xtmax is a chord-wise distance between a leading edge (18) and a maximum thickness position; and (c) a ratio taft/tmax of taft to a maximum blade thickness tmax is not less than 0.51 and not greater than 0.56 where taft is a blade thickness at a midpoint on a chord (34) between the maximum thickness position and a trailing edge (20).