Flatback Slat for Wind Turbine Blade Aerodynamic Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The inboard portion of wind turbine blades is aerodynamically inefficient due to high variations in angle of attack, structural limitations, and thick airfoil shapes, leading to stalled conditions, reduced lift, and low torque contribution to wind energy conversion.
Innovation Solution
The implementation of a flatback slat with a flat trailing edge and vortex generators, positioned behind the mean camber line of the main blade, to optimize lift over a broader range of operating conditions, attached to the spar cap for enhanced stability and ease of installation, and equipped with a splitter plate to prevent vortex shedding and extend aerodynamic influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the inboard portion of the blade is made thick to support centrifugal and lift loads, then structural strength is improved, but aerodynamic efficiency deteriorates due to structural limitations in airfoil shape and high angle of attack
Solution Approach 1:
The blade is segmented into multiple airfoil sections along the span, with each section having optimized thickness and airfoil shape. The inboard portion maintains sufficient thickness for structural strength while outboard portions use thinner, more aerodynamically efficient shapes, resolving the contradiction between structural requirements and aerodynamic performance
Solution Approach 2:
Different airfoil sections are designed with locally optimized properties - the inboard portion has thicker cross-sections for structural strength while maintaining appropriate airfoil camber and twist, while outboard portions have thinner sections optimized for aerodynamic efficiency. This local differentiation allows each section to perform its primary function optimally
2Ease of manufacture
If the chord angle or twist angle of the blade is kept constant for manufacturing reasons, then manufacturing ease is improved, but aerodynamic performance deteriorates due to excessive angle of attack proximate the root
Solution Approach 1:
The blade incorporates spanwise variation in chord angle and twist angle, with the inboard portion having smaller angles and the outboard portion having larger angles. This local differentiation optimizes the angle of attack at each radial position, improving overall aerodynamic performance while maintaining manufacturing feasibility through modular construction
Solution Approach 2:
The blade design incorporates dynamic adjustment capabilities through pitch control mechanisms that can modify the effective angle of attack in response to operating conditions, allowing the blade to maintain optimal performance across varying wind speeds while keeping the static geometry relatively simple for manufacturing
3Productivity
If flow altering devices including slats and flaps are added to wind turbine blades to improve aerodynamic performance, then aerodynamic efficiency is improved, but device complexity increases
Solution Approach 1:
The patent extracts and addresses the primary flow control function through optimized airfoil geometry and twist distribution built into the blade structure itself, rather than adding complex mechanical slats and flaps. This integration reduces device complexity while maintaining aerodynamic benefits
Solution Approach 2:
The patent introduces intermediate flow control elements such as vortex generators or small passive fences that mediate between the simple airfoil shape and the need for flow control. These intermediate devices provide aerodynamic benefits with minimal added complexity compared to full slat-flap systems
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
The flatback slat improves aerodynamic performance by maintaining consistent air inflow angles, reducing drag, and increasing lift across a wider range of angles of attack, enhancing wind energy conversion efficiency and power production.
Implementation Method 1
A stalled condition occurs when the angle of attack is too high and the air passing over the suction side of the airfoil detaches from the surface of the blade, creating a separated flow region
Implementation Method 2
The implementation of a flatback slat with a flat trailing edge and vortex generators
Implementation Method 3
equipped with a splitter plate to prevent vortex shedding and extend aerodynamic influence
Data Source
AI summary
An aerodynamic slat (30F) having a flatback trailing edge (44F) extending along and spaced proximate an inboard portion of a wind turbine blade (22). At least the leading edge (42F) of the slat may be disposed within a zone (48) of airflow that is generally parallel to the suction side (40) of the wind turbine blade over a range of air inflow angles. A splitter plate (52) may extend aft from the flatback trailing edge to reduce vortex shedding and extend the effective chord length of the slat. Vortex generators (60) may be attached to the slat. Flatback slats may be retrofitted to a wind turbine rotor (20) by attaching them to the spar caps (56) of the blades or to the hub spinner (28). The flatback slat provides lift on low-lift inboard portions of the wind turbine blade over a range of angles of attack of the inboard portion.