Wind Turbine Blade Lift Coefficient Distribution

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Solution Overview

Problem

Current wind turbine blade designs face challenges in achieving optimal aerodynamic performance due to limitations in determining airfoil shapes that meet desired design lift coefficients, particularly near the blade root, where transportation constraints limit chord length, and in maintaining consistent performance across different thickness ratios, leading to inefficiencies in electricity generation.

Innovation Solution

The design of wind turbine blades with a chord length increasing from the tip to the root, featuring a blade tip region with a constant first design lift coefficient, a maximum-chord-length position with a higher second design lift coefficient, and a transition region with a gradually increasing lift coefficient, along with specifying airfoil profiles using Y125, suction-side convexity YS, and pressure-side convexity YP to reduce variation and optimize aerodynamic characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the blade diameter is increased to generate more electricity, then the output power is improved, but the aerodynamic load on the blade increases

Engineering Contradiction:
Improveoutput powerVSAvoidaerodynamic load
Core Design Contradiction:
PowerVSForce

Solution Approach 1:

The patent applies different design lift coefficients to different regions of the blade. The blade tip region uses a first design lift coefficient while the maximum-chord-length position uses a higher second design lift coefficient. This local differentiation allows optimization of aerodynamic performance in each region while managing overall load distribution across the blade span.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent transitions the design lift coefficient from a constant value to a gradually increasing distribution from blade tip to root. This parameter change enables the blade to generate more power by optimizing lift distribution, while the gradual transition maintains aerodynamic efficiency and manages load increases.

Inventive Principle:
Principle #35Parameter changes

2Force

If the chord length is reduced to decrease aerodynamic load, then the aerodynamic load is reduced, but the blade efficiency decreases

Engineering Contradiction:
Improveaerodynamic loadVSAvoidblade efficiency
Core Design Contradiction:
ForceVSPower

Solution Approach 1:

The patent specifies different airfoil profiles with different thickness ratios at different radial positions. Thicker airfoils are used near the blade root where structural requirements are higher, while thinner airfoils are used toward the tip. This local differentiation maintains aerodynamic efficiency while managing load distribution.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs a dynamic airfoil design where the thickness ratio and airfoil profile characteristics vary continuously along the blade span. This dynamic configuration allows the blade to maintain optimal aerodynamic performance across different operating conditions while managing load distribution.

Inventive Principle:
Principle #15Dynamics

3Power

If the chord length is increased near the blade root to improve aerodynamic performance, then the aerodynamic performance is improved, but the transportation becomes difficult due to size constraints

Engineering Contradiction:
Improveaerodynamic performanceVSAvoidtransportation
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The patent optimizes the thickness ratio parameter at different radial positions to achieve high aerodynamic performance. By carefully selecting thickness ratios that balance performance and structural requirements, the blade can be designed with efficient aerodynamics while maintaining a chord length that is feasible for transportation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies a higher design lift coefficient specifically at the maximum-chord-length position rather than uniformly across the entire blade. This partial application of high lift coefficient achieves improved aerodynamic performance at the critical root region while keeping the overall blade dimensions within transportation limits.

Inventive Principle:
Principle #16Partial or excessive action

4Power

If different airfoil shapes are used to achieve desired design lift coefficients, then the aerodynamic characteristics are optimized, but the manufacturing complexity increases

Engineering Contradiction:
Improveaerodynamic characteristicsVSAvoidairfoil shape specification
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent specifies different airfoil profiles with different thickness ratios at different radial positions to optimize aerodynamic characteristics locally. This differentiation enables tailored performance optimization while the systematic approach to selecting and transitioning between profiles manages manufacturing complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs a dynamic airfoil design where profile characteristics vary continuously along the blade span. This systematic variation of airfoil parameters creates optimized aerodynamic performance while providing a clear, repeatable manufacturing process for producing the varying geometry.

Inventive Principle:
Principle #15Dynamics

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 approach allows for improved aerodynamic performance and reduced load on the blades, enabling the design of longer blades that generate higher electricity output while minimizing noise and maintaining desired aerodynamic characteristics under transportation and operational constraints.

Implementation Method 1

the airfoil (blade section) have the following characteristics: 1. High design lift coefficient 2. Optimum 'combination' of design lift coefficients

Methodology Applied
Scientific EffectBernoulli effect: Bernoulli Effect

Implementation Method 2

the distance from the chord on the suction side, at a 1.25% position... the distance from the chord on the suction side, at the maximum-thickness position... the distance from the chord on the pressure side, at the maximum-thickness position

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Implementation Method 3

wind turbine blades rotate axially by means of wind force, and the rotational force is converted into electricity

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 4

wind turbine blades rotate axially by means of wind force

Methodology Applied
Scientific EffectWind force: Wind Power

Data Source

PatentEP3179095B1Wind turbine blade, wind power generation system including the same, and method for designing wind turbine blade
Publication Date: 2020.03.04 MITSUBISHI HEAVY IND LTD
  • EP3179095B1 patent drawingFigure 1
  • EP3179095B1 patent drawingFigure 2
  • EP3179095B1 patent drawingFigure 3

AI summary

Provided is a wind turbine blade that delivers the desired aerodynamic characteristics under conditions where the upper limit of the chord length near the blade root is limited. The wind turbine blade includes a blade body (3) whose chord length increases from a blade tip (1b) toward a blade root (1a). The blade body (3) includes a blade tip region (1c) located near the blade tip and whose chord length increases gradually toward the blade root (1a), the blade tip region (1c) having a substantially constant first design lift coefficient, a maximum-chord-length position (1d) located near the blade root (1a) and having a maximum chord length, the maximum-chord-length position (1d) having a second design lift coefficient higher than the first design lift coefficient, and a transition region (1e) located between the blade tip region (1c) and the maximum-chord-length position (1d). The transition region (1e) has a design lift coefficient increasing gradually from the first design lift coefficient to the second design lift coefficient in a direction from the blade tip (1b) toward the blade root (1a).