Wind Turbine Rotor Blade with Optimized Solidity Ratio
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Solution Overview
Problem
Conventional wind turbine blades experience high loads, particularly at the blade roots and tips, leading to increased costs and reduced efficiency in wind farms, especially under extreme conditions and partial wake operations, with existing load reduction methods being ineffective or costly.
Innovation Solution
A wind turbine rotor design with a unique chord distribution and lift enhancing features, where the solidity ratio between radial positions is optimized to reduce axial induction, allowing for passive overload protection and improved aerodynamics, particularly at higher tip speed ratios and lower wind speeds, and incorporating lift enhancing means to enhance energy production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional blade designs are used, then the turbine can generate power, but high loads are produced at blade roots and tips increasing structural costs
Solution Approach 1:
The patent applies different chord lengths to different radial positions of the blade, creating local variations in blade geometry. The chord length is optimized at each radial position to control the axial induction distribution, with shorter chords at certain positions to reduce induction and longer chords elsewhere to maintain power generation. This local optimization resolves the contradiction by allowing power generation while reducing loads at critical locations.
Solution Approach 2:
The patent changes the geometric parameters of the blade, specifically the chord length distribution along the span. By modifying the chord length parameter at different radial positions according to the invention's criteria, the axial induction is reduced, which subsequently reduces the blade root bending moments while maintaining acceptable power generation capability.
2Strength
If blade chord length is increased to reduce induction, then loads are reduced, but power generation capability decreases
Solution Approach 1:
Rather than uniformly increasing chord length, the patent applies local quality by varying chord length at specific radial positions. The chord is shortened at positions where high induction causes excessive loads, while maintaining or increasing chord length at positions where power generation is prioritized. This selective approach resolves the contradiction by locally reducing induction without globally sacrificing power generation capability.
Solution Approach 2:
The blade is segmented into different radial zones, each with optimized chord length characteristics. The blade span is divided into regions where different chord length strategies are applied - some regions with shorter chords to reduce induction and loads, and other regions with adequate chord length to maintain power generation. This segmentation allows simultaneous optimization of both load reduction and power generation.
3Strength
If active control methods are used to reduce loads, then loads are alleviated, but maintenance frequency increases
Solution Approach 1:
The patent implements passive load reduction through geometric design rather than active control systems. The blade's chord length distribution is optimized to inherently reduce axial induction and loads during normal operation, eliminating the need for active actuators, sensors, or control systems. This self-service approach resolves the contradiction by providing load reduction through the blade's static geometry, avoiding increased maintenance requirements.
Solution Approach 2:
The patent replaces complex, expensive active control systems with a simple, passive geometric design. The chord length distribution is a fixed structural feature that provides load reduction without requiring ongoing maintenance, replacement, or complex control electronics. This substitution of a simple geometric feature for complex active systems resolves the contradiction between load reduction and maintenance requirements.
4Strength
If peak shaving is applied to reduce loads at rated wind speed, then some loads are reduced, but effectiveness is limited under extreme conditions
Solution Approach 1:
The patent implements preliminary action by designing the blade's chord length distribution in advance to prevent excessive induction and loads before they occur. The geometric optimization is built into the blade structure, creating inherent load reduction capability that operates automatically across all wind conditions without requiring real-time control actions. This preliminary design approach resolves the contradiction by providing reliable load reduction that works consistently under both rated and extreme conditions.
Solution Approach 2:
The blade geometry itself provides the load reduction function through its optimized chord length distribution, without requiring external control systems or active intervention. The passive geometric design automatically adjusts the aerodynamic characteristics to reduce loads under varying wind conditions, providing reliable and consistent effectiveness. This self-service mechanism resolves the contradiction by making load reduction inherent to the blade design rather than dependent on active control reliability.
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 blade root and tip loads, enhances energy production at lower wind speeds, and provides passive overload protection, increasing the efficiency and yield of wind turbines while minimizing structural costs, especially in larger turbines.
Implementation Method 1
the axial induction induced by a rotor with such blades is close to 0.3 in the rotor centre and considerably lower at larger radial positions
Implementation Method 2
the lift produced by the blades is reduced
Implementation Method 3
the power coefficient at lower wind speeds is relatively high so that a larger fraction of energy is produced at lower wind speeds
Data Source
Figure 1
Figure 2~3
AI summary
Wind turbine comprising a rotor blade, characterized in that the sol(r1Ir2), which is the ratio of the solidity at radial position r1 and the solidity at radial position r2, at a of the r1/r2 combinations specified in the table is larger than any of the associated values in the table. sol (0.3R/0.5R) sol (0.5RI0.7R) sol {0.7RI0.9R) preferred 1.45 1.5 1.5 more preferred 1.5 1.6 1.65 most preferred 1.6 1.7 1.8 Rotors according to the invention reduce loads such as in particular blade root bending moments, tilt moments and yaw moments. Furthermore they increase wind farm efficiency and reduces wind farm loads. The wind farm effects become even more beneficial when turbines at the upwind side in a farm are operated at lower tip speed ratio than turbines at the leeward side. According to a particular embodiment of the invention the rotor blades are equipped with lift enhancing means.