Vertical Axis Wind Turbine Rotor with Deflected Wings
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Solution Overview
Problem
Wind turbine rotors with vertical rotation axes face issues of high bending stress, aerodynamic drag, and self-excited aeroelastic vibrations due to pulsating loads and centrifugal forces, leading to reduced efficiency and wear, particularly exacerbated by the asymmetry of aerodynamic forces on upper and lower wings.
Innovation Solution
The rotor design features deflected wings with chord lengths and thickness decreasing towards the tips, where the upper and lower wings are radially deflected at angles relative to the rotating axis, with the chord lengths and thickness in the central zone inversely proportional to their radius, reducing bending moments and introducing aerodynamic twist to stabilize wind power consumption and prevent flutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional strengthening elements (line tie rods or additional supports) are inserted into the rotor construction to stiffen the wings, then the stiffness and durability are improved, but the aerodynamic drag increases and turbine efficiency decreases
Solution Approach 1:
The patent applies local quality by varying the chord length and airfoil thickness along the span of the rotor blade. The chord length is longest at the root and decreases towards the tip, while the airfoil thickness is greatest near the root and tapers towards the tip. This non-uniform distribution provides maximum stiffness where needed (near the root) while minimizing aerodynamic drag in the outer regions where the strengthening elements would otherwise be required.
2Stress or pressure
If the chord length and thickness of the airfoil are decreased towards the wing ends to reduce centrifugal force effects, then the bending stress is reduced, but the aerodynamic efficiency decreases
Solution Approach 1:
The patent applies parameter changes by systematically varying the chord length and airfoil thickness as continuous functions of the radial position along the blade span. The chord length follows an inverse relationship with the radius, and the airfoil thickness decreases proportionally, creating an optimized gradient that balances structural requirements (reducing bending stress) with aerodynamic performance (maintaining efficiency).
3Power
If the rotor operates at high speeds to increase power output, then the energy production increases, but self-excited aeroelastic vibrations (flutter) occur
Solution Approach 1:
The patent applies curvature by giving the rotor blades a twisted three-dimensional shape rather than a straight configuration. The blades are curved along their span with the chord line oriented at an angle to the plane of rotation, creating a helical or swept-back geometry. This curvature introduces aerodynamic stability that suppresses flutter and other self-excited vibrations, allowing high-speed operation without compromising reliability.
4Power
If the wings are made longer to increase power capture, then the energy production increases, but the bending moment from centrifugal force increases
Solution Approach 1:
The patent applies local quality by concentrating the structural reinforcement (greater chord length and airfoil thickness) in the inner regions of the blade where the bending moment is highest due to centrifugal forces. The outer regions have progressively smaller dimensions, reducing mass and centrifugal loading. This non-uniform distribution allows longer overall blade span for increased power capture while maintaining acceptable stress levels through localized strengthening where it is most needed.
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 enhances stiffness and durability, reduces aerodynamic drag, and maintains high efficiency by stabilizing wind power consumption and preventing flutter, especially during gusts, while balancing aerodynamic forces across the rotor length.
Implementation Method 1
The deflected wings introduce aerodynamical twist - angle of the incoming air flow near the central zone of wing is bigger than at the wings end. The diversity of angle attack in practice eliminates the danger of flutter.
Implementation Method 2
The frequency of free vibrations of blades with deflected wings and decreasing chord and thickness of airfoil is higher than that of straight blades. This facilitating result is particularly visible during gust winds. The diversity of angle attack in practice eliminates the danger of flutter.
Implementation Method 3
During the rotor movement exerted by the wind pressure apart from the driving aerodynamic force, there is also centrifugal force. Both forces act in the centres of the mass of two wings. Both forces on half of the circular trajectory of the blade rotation are directed to the same direction - resulting in the longitudinal deformation of the wings and high bending stress in the connection zone of the blade and the support.
Implementation Method 4
During the rotor movement exerted by the wind pressure apart from the driving aerodynamic force... The use of the rotor with deflected wings which, at the same time have decreasing chord thickness of wings airfoil towards their tips, provides a stable intensity of wind power consumption along the length of the wings.
Data Source
Figure 1~3
Figure 4~5
AI summary
The rotor has, connected with the hub (1), at least two horizontal supports (2) on the ends of which are rotor blades (3) of a symmetrical and concavo-convex aerodynamic profile with the chord lengths (b1, b2) and the thickness of the profile diminishing towards both wing ends (3a, 3b). The upper wing (3a) and the lower wing (3b) of the rotor blade (3) are radially deflected from the central zone (3c) outwards. The length of the chords (b2) of the profile of both wing ends (3a, 3b) and the chord length (b1) in the central zone (3c) are approximately inversely proportional to the radii of its location in relation to the axis of the rotor's rotation. The deflecting angle of the lower wing (3b) can be greater than the deflecting angle of the upper wing (3a) or the length of the lower wing (3b) can be greater than the length of the upper wing (3a). The specification of the rotor gives a uniform intensity of consuming wind power at the length of the wings and generally in the support only tensile stress is generated while the hazard of flutter is practically eliminated.