Stiffened Bend Wind Turbine Blade Tower Clearance
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Solution Overview
Problem
The design of conventional wind turbine rotor blades is limited by a clearance threshold distance from the tower, leading to potential contact and damage during deflection, as they act like beams and 'open up' despite flapwise curves, posing a risk of striking the tower.
Innovation Solution
The rotor blade features a bend between an inboard and outboard portion, stiffened to reduce opening during deflection, which relocates the point of closest approach to the tower, allowing for improved clearance and performance by extending the outboard portion outwardly and incorporating stiffening features like internal stringers and a joint sleeve to maintain tower clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional rotor blade design with flapwise curve is used, then general aerodynamic performance is improved, but during extreme deflection the blade tips still open up and may strike the tower
Solution Approach 1:
The rotor blade is segmented into distinct portions (inboard portion, bend, outboard portion) with different structural characteristics. The bend region is specifically designed as a stiffened segment to prevent opening during deflection, while other portions maintain aerodynamic optimization. This segmentation allows different regions to serve different functions simultaneously.
Solution Approach 2:
The blade structure is not uniform but has local quality variations: the bend region has enhanced stiffness through internal stringers and joint sleeves, while other regions maintain optimized aerodynamic properties. This localized stiffening at the bend prevents tip opening without compromising overall aerodynamic performance.
2Reliability
If rotor blade is designed to maintain tower clearance with traditional beam-like structure, then safety is improved, but blade performance and efficiency are limited
Solution Approach 1:
The rotor blade incorporates a curved bend region instead of a straight beam-like structure. This curvature allows the blade to maintain clearance from the tower during deflection while preserving aerodynamic efficiency. The bent configuration optimizes both safety clearance and performance characteristics.
3Productivity
If rotor blade length is increased to improve performance, then energy capture is improved, but risk of tower contact during deflection increases
Solution Approach 1:
The blade design transitions from a simple linear extension to a three-dimensional curved structure with a bend. This dimensional change allows the blade to achieve greater effective length for energy capture while the curved path maintains clearance from the tower during deflection, resolving the conflict between length and safety.
Data Source
AI summary
In one embodiment, a rotor blade includes a tip, a root, and a body extending between the tip and the root. The body has surfaces defining a pressure side, a suction side, a leading edge, and a trailing edge. The body further defines an inboard portion, an outboard portion, and a bend therebetween. The bend is defined such that the outboard portion extends outwardly with respect to the inboard portion. The bend is stiffened to reduce opening of the bend during deflection of the rotor blade.